New wave of car makers too, Tesla's first was built on a Lotus platform.

Will purpose built EVs have better ride quality than an ICE platform with electric motor?

I'm not sure what the ride quality has to do with that - it's 100% down to the suspension setup and choices made by the manufacturer, regardless of the drive train. You can have a small city car with amazing plush suspension, and a big long distance cruiser saloon with break-my-back suspension because for some reason the manufacturer made it "sporty" and "nurburgring tuned" - different strokes for different folks.

> I'm not sure what the ride quality has to do with that - it's 100% down to the suspension setup and choices made by the manufacturer, regardless of the drive train

Suspension isn't infinitely adjustable without other tradeoffs, including cost. Batteries are already very heavy compared to ICE drivetrains.

That might be fine for an expensive car like an Audi or BMW that have a high end suspension anyways (probably even driver adjustable), but that probably won't fit into the budgetary constraints of a more affordable vehicle.

First gen EVs also didn't have lithium batteries.