The long term future of any particular configuration management system
From my perspective, one of the problems with the current profusion of configuration management systems is exactly that there is a profusion of them. I don't have a problem with choice per se (or having to sort through them all); for me the issue is the uncertainty that this creates for the long term future of any particular system.
Right now we have a lot of CM systems; off the top of my head I can think of CFEngine, Puppet, Chef, Ansible, and SaltStack, and there are probably others. It seems unlikely that they will all survive as actively developed and used systems over the next five to ten years. Some of them certainly will but probably not all (and I kind of hope that not all of them survive, because if they all do that's a lot of duplicate or near-duplicate effort).
Unless you're confident in your ability to pick winners and losers here (which I'm certainly not), the net effect of this is to add more uncertainty about the long term costs and payoffs of using any particular current CM system. If today you pick what turns out to be a loser in five years, well, that's all the payoff time you're getting (and now you'll have the costs of switching what's likely to be a well-developed environment to another CM system). At least for me this drives up the short term payoff I want to see from a CM system before it seems worthwhile to switch to it and I keep having problems seeing that.
(I don't have a good answer to this issue. I'm not sure there is one. And certainly my deep-seated skepticism that a CM system wouldn't be a big win here is part of the general issue; if I thought a CM system would be a significant improvement, well, I'd have that short term payoff. Instead I'm left feeling that I'd get at best a small incremental improvement over the short term.)