I am not sure which landlines you remember, but VoLTE voice quality is better than every phone I've ever used, from landlines in the 80s to VoIP Vonage phones. POTS systems ran at a lower quality than current phones.
I've never had a cell phone that can match the latency of a 80s or 90s landline for local calls. Maybe the audio is as good, but that delay makes calls distinctly worse.
Latency is a different thing, though. Yes, latency is worse in some cases than copper-connected phones were, but that's a highly subjective statement relative to the connections. But quality alone has never been higher than it was, and it was much lower on landline phones.
The audio is awful. The old landlines advertised hearing a pin drop. And no one laughed at that concept. Imagine trying to hear something comparable with today's mobile phones.
Yeah, I think so too; modern cell phone voice quality has been pretty good in my experience. Granted, I'm mostly only calling other cell phones, so maybe there could be a quality downgrade if you call something truly analog that's still attached to a landline?