Yes 24 GB is definitely not overkill if you're doing all that. I also hesitated between a MBA and a MBP, I ended up with a MBP with 16GB of RAM and that's definitely the limiting thing. Not that I feel it's outdated already obviously, but it might not last as many years as I wished. I'll probably wait until that computer is outdated to upgrade, probably to a lighter MBA.
I'm still curious why you updated so early to get a machine "to last just as long" if you think that 16 GB of RAM is not preventing you from what you're trying to achieve - but you probably had other reasons.