Well, its not quite the same as Russia - USSR, the Mughals were foreign Muslim kings who invaded India but basically liked it so much they turned what was supposed to be a colonial holding into their own nation and thought themselves the true rulers of india. The maurya came like roughly 1000 years before the mughals, which is your first big difference!
they were the first people to unite the subcontinent, which is no mean feat in 400 BC, making them more worthy than most, which is why its kind of annoying that they are represented by the big bloob. I could go on about it but thats the 2 most important groups, personally, that really do deserve their own civs. Its not like Russia USSR, more like Rome - All of europe ever hahah
Civilization is different to dynasties, political entities and so forth though. The Mughal Empire was an Indian Empire, no matter who ruled it. Yes, they were Persian rulers, much like the Qing Dynasty were Manchurian, that doesn't make it "Not India" suddenly.
Persia also had various dynastic rulers over the eras, but they are in the game rightly as Persia as a whole. India clearly has been meant to represent the various previous dynasties and rulers as India as a whole, and breaking it up into various dynasties and such is better left to the various Paradox games.
A Tamil civilization would be interesting especially consider the difference between the Indo-Aryan north and the Dravidian south.
Afghans instead of Mughals would be preferable as Muhammad of Ghor ruled a vast swath of northern India. The current India could represent the Indo-Aryan Hindu civilization of most of India through its recorded history.
Tamil, whilst interesting, is hardly the most significant of Civilizations. It certainly could be represented on their own, but so could a massive host of cultures also not in the game.
Afghanistan is an interesting suggestion though.
I would argue China is less of a blob than people think - the concept of a unified China, at the least, has existed in some form since ancient times with the Middle Kingdom. When China broke into little warring states, they always wanted to re-unify China and restore the Middle Kingdom, essentially - India never had this sort of concept until very recently. All the great empires that managed to rule over large portions of the Indian subcontinent - including the Mauryans and the Mughals - never managed to get India the level of unity that China did. These great empires did not consider themselves true successors of each other the way that the Chinese dynasties did. (Do note however that when I speak of China I'm not including Manchuria/Tibet/Xinjiang, I'm referring to the core area of modern-day China that people associate with the Chinese civilization)
That said, as others have suggested, one way to go about the India split is basically to do north-south. So the current India can remain, representing the north, while we can have a Tamil/Chola/whatever civ for the south. This isn't too unreasonable, as there is a definite linguistic and even cultural split between the Indo-Aryan-speaking north and the Dravidian-speaking south.
Don't forget Inner Mongolia when talking about parts of China that are historically not "Chinese" as such. Of course, they could never split China for political reasons, and that includes Tibet, Xinjiang and Manchuria.
A North-South split of India could work, but the question then becomes of the overall significance of the Tamil culture. A Civilization in the game can be included for various reasons:
1. Historical significance
2. Modern Significance
3. Marketability
4. Gameplay elements
But a Tamil Culture doesn't really seem to fit this as such. It's more a case of offering more cultural diversity to the sub continent, which could be done in other ways, one of which would be having Civilizations such as Sri Lanka or even Burma. Tamil are certainly an option though, but I don't think it's the most obvious choice. It certainly wouldn't force a "split" of India either.
Speaking of blobs though, the only real blob we have in the Civ V is Polynesia, and even they have some level of uniting culture. The issue is how to deal with Polynesia otherwise, as they are a very interesting and impressive culture that do deserve to be in the game for being very interesting and unique as well as offering something interesting to the game as a whole.
I'd also add that one thing I hope the game keeps away from is Dynastic names. The only one that jumps out right now is the Ottomans on that front though, and they could be renamed to Turkey in future versions.
I hesitate to disagree with you, because I almost always agree with your opinions and the field is littered with the bodies of those who have tried. However, I do disagree when it comes to Ancient Israel. I think they can stand on their own. In terms of military power, obviously you are correct that it was not as powerful as Rome, Greece, Persia, Carthage, Egypt or Babylon and several others. (However, I think it is worth noting that, unlike Greek, Egyptian and Hittite societies, Ancient Israel was not destroyed by the Sea Peoples. That should be worth something.) I think Ancient Israel has left a great mark on our society, greater than many ancient societies, which eventually were subjugated by even greater military powers and often left no indigenous written record. The writings that Ancient Israel's learned left behind continue to play a key role in philosophical discussions, particularly ethics, as they have for millennia. Isn't a nation that left such an indelible imprint on human thought, ideas and philosophy, as well as religion, one that should be included? When you consider our daily lives, even as an atheist (as I am), I acknowledge the profound impact that thinkers and writers from Ancient Israel have had upon my thought process every single day when I ponder bigger questions about life and how we should treat each other.
We have sadly been asked to not discuss Israel here, which is a shame as there is much to discuss on this topic though this is not the place.