Agree with the OP, the patch has made the game less fun (and no, I'm not playing it above King level). Instead of being easy and boring, it's now hard and boring. Post-patch, I'm now 50% sure this game is a dead duck, simply because patches are too reactive, there is evidence of throwing in quick fixes without proper game testing or even much thought as to how they impact the overall game mechanic. If this continues, the game will start to 'thrash', oscillate wildly in terms of expected outcomes, with continued predictable outrage by dedicated Civ fans.
So, here's a constructive suggestion. Just for a start, hexes are neat, and curbing SoDs is a good idea, as long as the insanity of 1upt, which the AI can't handle, is avoided. Firaxis still has the codebase for Civ4 right there. Retrofit Civ4 with - just for starters - hexes (though hopefully not the dire graphics of Civ5, those cities look ugly, Civ4 cities were a handsome thing to behold), and add a stacking limit (in fact make this tweakable by the player up to some maximum value, maybe 12). I'm sure there may be a few good other things from Civ5 that could be retrofitted too (perhaps Natural Wonders, for example, not the Disneyland ones tho). Then release this as Civ4.5 *at a modest price* (and hopefully on Steam, making existing Civ4 installations dependent on that risks alienating a whole new bunch of people - big time). Stack it high, sell it cheap. And never ever forget that incremental development is the way to go.
The point is that a Civ4 retrofit should be cheap, not merely in coding, but in the vital playtesting. That is a mature codebase that is not thrashing. But by all means don't phase out Civ5, run the two in parallel - it's not impossible that the company could make money from both, there is a market for simplified games like Civ5 obviously.