Sorry, I really dislike latest changes.
Don't apologize, you are free to express opinions!
First of all, Aforess, you've said that you will find a way that smaller civs ( with 1-2-3 cities) can play too. But this changes are completely opposite this goal!
Why do you think so? Do you have evidence that this harms smaller civilizations?
From my experience smaller civilizations tend not to keep up in terms of city size and specialization, so flat commerce and yield benefits them more than a multiplier would. Yes, the multiplier reduction hurts big cities. It was ridiculous to have cities with +200%

or +150%

and +150%

. I didn't remove all multipliers because, as you say, it would defeat specialization. It is still very attainable to have +100%

or +100%

, just harder.
The game is much more balanced now. Before these changes it was necessary to give smaller civilizations 100's or 1000's of free science beakers a turn by tech diffusion just to keep up. Now they can get a fraction of that and still maintain pace.
Now, big cities is seriously weaker. It is the second nerf them after trade routes. Now you HAVE TO create many cities to play, it is impossible to play with 3-4 cities, and don't suck on science.
Multipliers benefited larger civilizations more than smaller ones. Larger civilizations could afford to build all the buildings, attain more multipliers, and tech faster (leading to more buildings, more multipliers, and so on)
So, you speaking one, and doing another, isn't it?
I don't think I am, but feel free to prove me wrong.
And I suppose it is a global balance change, it should be discussing on forum. It influence the game style even more than trade routes. And there was no discussion, you only change everything as you decision.
There is discussion, right here. That's what I want. It's better to make changes, test, and discuss than sit around in a committee all day theorizing about what might or might not work. We can test what works, change back what doesn't. We use source control (svn), history of changes are never lost.
Does it only my feeling that latest changes - in wrong direction? Diplomacy and trade was destroyed with removing trade routes, and now city specialization is destroyed with latest revisions. The game becoming one if it "warmonger" games.
I'm trying to do just the opposite. I don't want warmongering to be the only strategy to victory. Before revision 750ish, conquest was the only attainable victory condition. If you have been paying careful attention, you would notice that I have left cultural multipliers almost completely untouched by my changes. That makes a culture victory easier, while the reduced hammers make warmongering harder.
P.S. I have read the c++ code of finding best trade routes. There are tons of possibilities to optimize it. Saying it as pro in algorithms&maths. So, if the problem with trade routes in performance - I think it is not the problem, it is solvable.
Performance was the least of the problems with trade routes. The largest problem was that it was an opaque, hidden mechanic that gave players no control.
Also I find the claims that trade routes mattered for diplomacy very curious. I know for myself, that I never once considered the diplomatic value of trade routes until after I had removed them and a few players complained. Maybe you should run a poll, and find out if anyone other than yourself actually cared?