imo, ending app names in "str" is a form of branding; They are Nostr apps, and to symbolize that, we add "str". Still valid point.
Discussion
Yes, it started out as a brand, but it has a limiting effect, now, and it creates a first-past-the-post naming scheme.
You can have more than one solution, but only one can end in "str".
The road to hell is always paved with good intentions.