I remember being blown away at the quality of the effects in 1987. So much better than what was available for TV in the 60s. That the original resolution is considered "unwatchable" now is baffling to me.
Then again, I prefer the original TOS episodes to the remastered versions. I must be getting old. :/
You're right about the quality of effects, they are amazing, it was just hidden under a veneer of generational analog editing/duplication issues. The remastering of TNG proves, that when the original filmed elements are reconstructed in a modern digital video editing pipeline they look amazing.
As TV sizes have gotten larger and the resolution has increased, TNG has gotten much harder to watch. The inherent issues with the way they post-produced the series on video tape is greatly exacerbated on a 60" HDTV for example.