The problem is that if DL downgrades the F product, people will feel less inclined to pay full-fare for F. In the 90's (correct me if I'm wrong), the majority of the F cabin were filled of people on either paid F or true full-fare Y. Back in these days, DL (and other carriers) provisioned an elaborate meal service, had a nice presentation (linens, china, meals served in courses on shorter flights, even, etc), and made the F cabin attractive enough to pay for (menus, presentation, good meals). Then, DL (and others) cut, cut, cut, enhanced, enhanced, and enhanced. Result? Nowadays F isn't worth paying for.

If there was a ~$150 difference; I wasn't on a tight budget; and the flight was long enough (4.5+ hours; mostly transcon flights), I would pay for F. However, if AA/CO were offering similar routings in F at the same prices, I would rather pay for their F cabin, as both AA/CO offer differentiated transcon F (menus, sundaes, etc) during DL only offers JFK-LAX/SFO in BE-lite.

Unfortunately, from my perspective, DL's current F isn't attractive. Plopping everything on one tray, no linens, no transcon special service (excluding JFK-SFO/LAX), and generally having a cheap feel... is it worth it to me? No. Not except for the reasons listed above. I suspect many feel the same way. This is a self-fulfilling prophecy for DL, and they'll continue to cut until F is nothing but a bigger seat and some snacks/limited free alcohol. Hopefully they won't go this route, but who knows?