Just checked my Nokia collection... N800, E90, N8, N97, N900, N950, N9, E7, 920, 1020... Big screens, rock solid. Thicker than an iPhone? Sure. But most are thinner than the protective cases most folks I know put their iPhones in.
> Strong yes but it's also thick and plasticky with wide borders
A lot of people are pretty happy with that. For those that aren't, there's been a lot of progress in engineering in the past two decades since the 3310 came out.
It's not impossible to make something strong, while enjoying newer features. If we had a conscious choice in the shop between a slimmer phone that'll break apart in 6 months, and a thicker phone we could keep for 10 years, most people i know would choose the latter. There's just no such information for customers.
> The battery is tiny.
That was a technical limitation of the time and does not apply to today's batteries.
In other words: because of the construction method, lots of space is needed for structural elements.
Large glass screens require a rigid structure (or a border of some kind).