For context, I've started playing this summer, right now I'm building my Necramech and getting ready for The New War.
The story quests, in total, are about 10-15 hours of almost all killer no filler. They are not the issue. The real pain points are the grinds in between. Grinding out the amp so I could fight Umbra really made me love the game less, it's just so exhausting. Now that I'm on Deimos, even if the update itself is really cool and exciting, I'm just so cumulatively tired of the grind in between The Good Stuff, I can barely get myself to log on.
I'm not a marketing/sales guy, but I'm also not sure about asking new players to pay to skip the best content in the game. That's the content that gets them invested and turns them into hardcore players in the first place. I think the game is better off by asking devoted players to continue spending while finding way to convert more new players into regulars. I just don't believe this "oh I just wanna fiddle around with my friends, I don't really care about the game itself, but I'm still going to spend plat on skips" crowd exists. Warframe's competition is FFXIV, not Fortnite.
The ideal solution would be easing up on the grinds for non-mote amps, and adding an in-game roadmap that tells new players what they should do next, e.g. to ignore the open worlds and haul butt to Uranus, or that they need an amp to beat The Sacrifice.