There's been talk about why "wide" is preferred (optimal / more interesting), but without a detailed examination of the mechanics that support either playstyle. For example, AE, Coalition, Corruption, and Overextention, all in theory should hinder wide play, while Absolutism, Admin Efficiency, Reduced AE / Coring Cost, Fabricate Claim, Deus Vult / Imperialism / Nationalism CBs, etc. all encourage wide play. There's also broader concepts, like how total control of an end node is desirable for trade profit; or how developing up a province up is more expensive than taking an equal development amount of new land.
Personally, I find with each new expansion, the newly added gameplay elements are not very well cross-integrated, (with the exception of Development), do little to diversify how the game is played, and rarely receive follow-up attention. The biggest offender that comes to mind is Estates. It was advertised as a mechanic that would bring about more complexity to the internal country management aspect of the game. But I would say it failed at that promise; it is basically whack-a-mole with numbers attached. Once you've understood how to manipulate Estates at a basic level there's no further depth to it, no interesting decisions to make. As a result, peacetime gameplay was not enhanced, and many players find themselves still preferring the path of war. Beyond Estates though, I found it highly unusual for Paradox to introduce Corruption as this poorly thought out, arbitrary, short-term punishment for blobbing (which overlaps with AE and OE), and then later go back on it by introducing Absolutism. Given how celebrated Absolutism is vs how condemned Corruption is, I don't think it would be practical to try and discourage "wide" play through overt nerfs, even if I dislike how pro-blobbing mechanics are shaping the game. Instead, a better solution would be to make "tall" gameplay more attractive by making it more meaningful and interesting, with possibly added incentives. For example, what if there was a trade mechanic that preferred having a diverse amount of trading partners in your near vicinity? This would give tall players an incentive not to blob, to keep smaller neighbors safe, and maybe also encourage the breaking up of AI blobs.
Unfortunately the game is late in its cycle, and I don't have much confidence that we'll see an update that introduces a mechanic that truly changes how the game is played. The best example I can think of is Institutions, however Paradox's reluctance to address its criticisms (such as worldwide full institution embracement in the 1700s) shows to me that they're unwilling to devote more resources than necessary to make mechanics within the game more cohesive to the whole experience. On the other hand, Sailors did get a revisit, however, instead of becoming this new exciting gameplay concept that makes naval combat relevant, they just made Sailors have some small amount meaning, rather than the absolute meaninglessness they had previously. Unless the game is changed in a severe way, I think "wide" will remain in preference, and the 1700s+ will continue to see reduced play outside of WC attempts.
