Sure, if you just want upload / backup it's not worth it. If your currently happy with nextcloud then there is no reason to try immich.

But I highly recommend to sometimes view old photos to keep the memories alive.

I haven't looked into the nextlcoud add-ons, but didn't have a great experience with the ones I tried so far. In general I'm not really happy with nextlcoud even for file sync / share, but I haven't found any replacement, every thing else is much worse.