As someone who PuGs when PvPing as others have touched on the issue is when you reduce the Space SP allocation to 75% you decrease an individual player's options and effectiveness. This then requires more planning and coordination as a team to make up for the loses. This change will reward premades vs pugs. Most casually PvPers play on PuG teams, so in the end you'll still hear cries from casual PvPers.
For solo PvE w/season for changes there's been no reason to invest in ground SP as the gear came to be far more important than skills as fights became quick Boff dps spam vs enemy NPC dps spam.
For Sci Captain w/min SP investment (I didn't invest in battery skill but in some ground skill) I've had little problems in elite ground STFs (in terms of fighting borg, PuG PvE teamplay can still be an issue).
So, in the end my fun factor will go down, b/c I'll points in skills I don't need and I'll lose effectiveness if not out right abilities I'd otherwise have in Space. If my fun factor goes others will likely also and this would lead to people doing other things even if the game is for free to some.