Yabbers said pretty much what I was going to say, probably better than I am.
I don't think it's pointless for a store that's usually one of the better ones (in my experience) for disability access to extend a bit of kindness to others. I've been in there with a range of mobility devices from canes to mobility scooter, and I've never had an issue with other disabled people, pregnant women, or those with buggies. While I agree that it should be recognized that these were long fought for by disability activists and should remain centered that way, I really cannot get worked up over a store taking note that there is often space to make things easier for others.
And the "it's a choice" thing is often thrown at disabled people as well. Both my spouse and I have had people do this to us. I still remember the horrible nurse who assumed on my spouse's appearance that he was injured in a motorcycle accident (his choice to do something so reckless) when, actually, he survived an attack that left him lifetime disabilities and, either way, should not have be treated like crap. I've had medical professionals blame my "choice" (requesting my conditions be considered) for them screwing up and had a few be violent to "teach [me] a lesson". The 'it's a choice' rings a bit hollow for me.
I know more than a few who use buggies as or alongside mobility devices - I did it when mine were small alongside using carriers so I could have my hands free for needed devices - and plenty of pregnant women are disabled as well. While I don't recommend anyone be a doormat, it's also a choice to be kind, make things easier for someone, reduce suffering as well, you never know, you could make someone's day. I don't think that's pointless.