Grew up camping before slides and witnessed their development. So much less cramped.
As far as "one more thing to maintain", you can live without air/con, heat, running water, etc... and use the same excuse. The question is does it add enough benefit to outweigh the maintenance...in a heartbeat. Probably would choose slides over the furnace.
As someone else mentioned, expect to have a hard time selling when the time comes as 99% of the market will demand slides.
Also, where are you coming up with a lower price? Is that theoretical MSRP or actual negotiated offers from a dealer? A no-slide unit is likely to be a special order, so you likely won't get as big of a discount, if any compared to buying off the lot.