It's still our choice whether or not to farm zombies. I understand there are a lot of people who feel like they have to and why - zombies give much higher xp than other available options. But those options still exist and, personally, I've felt no need to go on a zombo killing spree expressly to level. In fact, my general playing style has become less 'kill the zombies' in A17 than otherwise.
The slower rate of materials gathering and the need to find alternate paths to iron tools early on has lead me to worry more about securing my food first (a concern I only had in A16 due to me being the main food hunter/gatherer in a group of six), and then my base because I can't just spend half a day hacking trees and have enough wood to lay down a sea of spikes. I've got to plan better, manage my time better, and look for other options.
I'm not entirely happy with certain aspects (I think the heavy reliance on RNG as alternate source needs to be altered a bit though I'm not sure of the best way to do that) but, IMO, farming is farming is farming whether I'm killing zombies to level or upgrading random blocks because my construction skill isn't high enough to buy the Steel Perk yet. I do think either zombie xp needs to be lowered or the amount of xp from other sources need to be upped (or both and we've been told this is being looked at and changed) and some of the level gates either need to be lowered (thank you bicycle) or alternate sources are more reliable. Perhaps the combination of the two will reduce the feeling of the 'need' to grind zombies.
I tend to like the concept of 'earn by doing' systems the best and can certainly understand why other people miss the old system. (I do too, to some degree.) However, I've played a lot of game that try that and every single one had glaring problems that resulted in the need to exploit the system, otherwise 'naturally' leveling some aspects worked fine while others either skyrocketed ahead to the point of being OP or lagged so far behind they were useless. Maybe those kinds of systems are just too unweildly or complicated to balance easily. If that's the case, then I'd rather have a simplified system that can be tweaked and added onto easily instead of one that's always painfully out of whack.
Edit: I should add that food gathering is relatively easy in A17. After a couple of days, I seem to get quite the haul.