Demon's Souls is just as much in need of a proper remake as DS1. There are major gameplay ooofs that scream for fixing - broken magic, awful UI and inventory, the terrible world tendency system (great idea, awful execution), the healing system (the DS-style rechargeable flask is vastly superior to the DeS/BB system), the retarded weapon upgrade system, the unnecessarily arcane crystal lizard system, the armour/poise system needs a complete rework (preferably in the DS2 style), useless mechanics like poison or bleed, absence of jumping, terrible PvP and a host of other minor issues (weapon balance, enemy encounters, build variety etc.).
And also, to be perfectly honest, I love the DeS gimmicky bosses, it's a wonderful reprieve from the fast jumping knight archetype spam in DS3, but many of them need some serious updating or even a straight up overhaul because in this day and age they'd be seen as extremely janky and lulzy.