You're older, and I bet you don't have tons of free time. I bet you also feel good sense of achievement from your work so you don't need an external source. Therefore, grinding for rewards doesn't appeal to you. I'm the same as you, grinding games do not appeal to me at all any more.
However there are tons of people who are not like that. I remember myself as a teenager, I used to *love* RPGs with grind mechanics, since it made me feel such a strong sense of accomplishment in a world where I (at the time) didn't get to feel that very often. It's not just teens either, it can be older people who just happen to have a ton of a free time, and not much else going on in their life. If you think about it, the grind emulates the real life experience of having a good career, only at a much faster pace. It's no wonder some people enjoy that. Sure, it's all 'fake' and they are usually aware of that themselves, but it still does genuinely make them feel happy.
Sure I am a little ashamed that I used to spend so much time playing those type of games as a teen, but overall I remember how good it felt at the time. If my career didn't inspire me (like 95% of people in the world), and I didn't have much else happening in my life, then I'm pretty certain I'd also be hooked on some mmorpg by now.