... Low tech having crappy frigates for example is not a themed thing that makes the playthroughs feel different, it's a problem that limits Low tech playthroughs. You are saying less options is more options and/or that less options is creating a good gameplay thing.
A bit more about the philosophy of gameplay here, but sometimes limits are what differentiates interesting gameplay. Like you say with low tech their current frigates are bad - so when I play lowtech I use Condors with Thunders (or other interceptors before I get Thunders) and do a decent amount of micro with their commands to fill the gap. The limitation makes me need to play in a new way.
When I play high tech I use their amazing frigate and wolfpack, but have no carriers below astral size to put interceptors on. There are things I can do with Tempests that Thunders can't do, and vice versa, so my anti-small ship strategy and gameplay are entirely different (and anti-large ship too, but that comes from other limitations in high tech).
Otoh, too many limits can be just as bad as too few limits; they need to be challenges to guide and overcome, rather than frustrations/impossibilities, and the perception of that can change from player to player.