The ST was a great computer but it's sometimes fun to think 'what if'. Would it have been possible for Atari to have released the STE in 1985? I don't think so. It would have been great to have had 1Mb RAM, SIMMs and double sided drives as standard from the beginning but it just couldn't have happened like that. Memory was very expensive in 1985. SIMMs had just been invented in 1983. It would have been amazing if Atari had thought about top and bottom border removal without having to use tricks, and hardware scrolling but then it would have been just like the Amiga.
I think it was a mistake for Atari to include single sided drives. It undoubtably made games producers limit games to fit onto a single sided disk just incase a few owners still had a single sided drive. This gave the packers a lot of scope to fit as many games as possible on a double sided disk though. At college in 1992 my mate had a ST with a single sided drive (and a double sided external drive with an A-B switch), a Macintosh SE (good for Word Processing) and a PC but played most of his games on the ST. Sim City, Oids, Stunt Car Racer and Xenon II mainly - all great games.
Still got, still working: Atari 4Mb STe, 520STFM, 2.5Mb STF.
Hardware: Cumana CSA 354, Ultimate Ripper, Blitz Turbo, Synchro Express II (US and UK Versions).