Let's be real: a lot of people are saying "Keyboard are really a personnal thing". Yes. Your own at home. The one you work with, however, is the one provided by the company. Period. People would complain a lot less about keyboards if management just enforced it or changed nothing.
Now, you're experimenting what we're taught in CS as "Change refusal". Users will stomp both feet down to avoid any change to their comfortable routine. You really want to buy X different keyboards for X different people, that won't be re-used after because next user will be "Oh no, I don't like this one, I prefer it pink"? The mouse click isn't what they like? Tough.1
From what you say about people complaints, I'd guess you're not working in a software company. Unless they're using a very specific setup, it make little to no difference for 90% of the users (barring the one that need specifically designed ergonomic keyboards). You can probably come up with a macro to open the calculator for those who ask for it. Or they can go to the extreme length of clicking at most three times to open it themselves. Even better, teach them to pin it to their task bar, and they will need one click.
I'm a dev. I know next to zero things about construction building. When I have to, I don't complain when the guy in charge provides me with a hammer that is slightly off compared to what I like.
What you did "wrong" 2 is allow them to pick the old "disgusting and/or broken" keyboard/mice back and make a fuss about it. Fix the missing key features, such as the "calculator button", things that could "hurt productivity" 3. Next time, ask what key features they need.
People will always find a way to complain. New keyboard? Forced change, unhappy. Old, falling apart keyboard? Management is too greedy to buy new one, unhappy. Truth be told, when there would eventually have been a problem with the old keyboard, people would have come for you anyway.
You did your job: you saw a problem, attempted to fix it and made a common mistake. Chalk it off as learning, fix the real issues. The unfounded whinings will stop over time. You just need to know them for what they are.
1: Plus, if you have X different keyboards, you will have to manage X different keyboards. Having the same one everywhere allows you to switch from a desktop to another, and spare you the unnecessary logistics.
2: and that's putting it boldly, you did your job
3: Trying so hard not to be sarcastic about your users, but it's hard.