I'm 100% with you. The X is one of the most awkward looking SUV's ever made, and the 3 looks awkward past the C pillar. In my opinion their best looking vehicle is the S because it looks correctly proportioned, and also because it has the semblance of a grille, even though it's just black plastic and doesn't actually function as a ICE car's grille.
As for the upcoming Roadster, that looks smashing. Too bad it's massively expensive.
I don't think I've ever been in a sedan that doesn't have this feature, but you usually get a little more space out of a hatchback if the roof-line doesn't taper down.
The Honda Fit and a few others are the exception but I assume the reason is that the SUV form factor has gobbled up most of the market for “hatchback with a lot of space for cargo”. E.g. Toyota discontinued the Prius V and is instead offering an electric RAV4.