Granted, the above was something of a pastiche responding to a claim that "gold is the be-all and end-all" in Civ V - you can play Civ IV in ways that don't emphasise science above all, but in exactly the same way you can play Civ V in ways that don't focus on gold production or trading (and I typically do). If there's an error, it's the failure to recognise in both cases that the games are both given to sandboxing of this sort.
However, Civ games are inherently games which have specific optimal strategies, and if your key goal is to win rather than to sandbox, there is a 'best way' to do so in Civ IV and that tends to involve maximising science. Your own examples below are mostly not of cases that actively improve your prospects of winning the game by cleverly adapting to the game situations you're presented with; they're just ways of doing things a certain way because you can - in a word, sandboxing. Sandboxing is not depth. I've made this distinction before - Go is a more complex game than chess because it has many more possible moves and hence strategies. It is not in any way a deeper game because, once you've settled on a strategy, the decision-making involved is no more complicated, and indeed is extremely similar. What defines a strong strategist is not how many options they have to reject, but how effectively they execute the one option they accept and how they adapt it to accommodate changing situations. Civ IV is no deeper in this regard than Civ V.
In Civ terms, Civ IV has many more improvement types than Civ V. But given certain terrain and a specific focus for your city, the decisions you make will be the same in both cases - if you have a production city, you want a mine on a hill in Civ IV. You want a mine on a hill in Civ V. The fact that you could instead have built a windmill in Civ IV but not Civ V does not add any extra depth to the decision-making process in that game.
Not often; my first reaction was typically to adopt Hereditary Rule, the default war weariness counter, since my cities need garrisons anyway, war weariness isn't much of an issue until the war's gone on for a while (and so all that time you're not producing science when you don't need the happiness boost is wasted), and see my previous comment on espionage.
I'll concede the others as I rarely played cultural games. But that comes back to the above - sure, for sandbox variety Civ IV beats Civ V every time. That's unrelated to the relative depth in either game.
