Does one NEED floor standing speakers for HT only?

Does one NEED them? In a word,no.

watching movies i would think that the sub would be a must. but what if i had real good fronts like b&w 801 nautilus? how would that even work for home theater? the processor for the surround sound would send only the lows to the .1 correct? this is through the sub out?

The processor would send only the LFE (.1 channel) via the subwoofer output if you so wished. OTOH, I use 800Diamonds with a subwoofer and bass management to send all the sub-40Hz bass as well. One reason is that the sub can be placed for optimal bass response without compromising that positioning for soundstage and imaging. In addition, there are many useful equalization facilities for subs, both built-in or add-on.

OTOH, I have been amazed and quite satisfied with a system based on 5 competent stand-mounted speakers with 1 or 2 good subs. There is no way for me, or anyone, to say whether going with the big speakers is worth YOUR money. Only you can decide.

N.B.: Good stand-mounted speakers take up as much floor space as floor-standers.

I would assume that the MIDS are what the floors would be bringing more to the table than the book shelfs? possible some of the lowers up to the sub. I will use a sub either way.

"MIDS are what the floors would be bringing more to the table"

That might be true, but for HT you should have center channel that usually has excellent mids. If you already decided to have sub (for special effects), then it might be better to invest in good center for the price difference between monitors and floor standers. Center channel in HT improves imaging for off center seats (widens sweet spot). Same goes for two subs - more even bass at different seating locations.