By default, the ult key, R, is used for many other things as well, and it's way to easy to accidentally use ult out of combat.
Either make it so that 'R' does not use the ult unless in combat; or at least give players the option to have that setting.
I rebound the key to a different key and it solved the issue entirely.
Another alternative: you can rebind all the controls, so if you want to keep the ultimate on the same key you could rebind all the other things which use the same one to something different.
I just changed the ultimate key to 6. So I have my regular skills on keys 1-5, and then my ultimate at 6.
When you rebind something, it will take you a few days to get used to it, but I promise you it will get easier and you will get used to it. It's been years now since I re-bound to 6 that I can no longer imagine any other key being my ultimate....
Have you never played other games? They all require you to remember different keybinds. Plus, this is the 21st century, where people have to remember PIN numbers, passwords, etc. Is it really that difficult to change the 'ultimate' keybind and remember it?Another alternative: you can rebind all the controls, so if you want to keep the ultimate on the same key you could rebind all the other things which use the same one to something different.
This is a much better solution, not forcing people to remember different keys than we've used for years.
There is no downside to letting players have this setting.