To me one very unfortunate thing about lack of skill points is that it seriously disincentivized takedown setups. Getting 3-6 or more kills after a chain and sidearm finish was a fantastic rush and you got a ton of points for stuff like that. Not that you couldn't still do it in 5, but getting a nice reward for the effort of setting it up was a huge part of what made it worthwhile. I didn't bother in 5 as much largely because of that, and also how takedown chains seemed oddly finicky and unwieldy compared to the earlier games.
I'm one of the apparent weirdos who liked the towers in FC. It could be argued that there may have been too many of them but it never really bothered me. I'd also argue that they simply evolved into the perk caches in 5, and if I had to choose between the two I'd take the towers every time. Some of the towers in 3 and a bunch in 4 involved some brief puzzle, similar to some the caches in 5, but the reward in 5 was almost always in some shitty dank cellar that I'd say was more repetitive and samey than the towers. Plus the towers being a tall vantage point in 3/4, you could actually see stuff around you and then wingsuit to wherever.
Clearly Ubisoft was trying to move away from its reputation of having samey gameplay among its franchises but the AC series where it started is the one I which I always found, and still find to be, the most tiresome in finishing its towers. Never bothered me in FC.