As someone who did a lot of embedded development, I wouldn't exactly call it "more interesting". More like "that shit needs to die already".

The biggest problem with those is, that modern compilers don't support it. Well, that is open-source compilers. IAR will happily sell you a license of their IDE for 2.4k$/seat. There is sdcc, but it's no comparison to a modern gcc or the commercial offerings.

Unfortunately you're right though, 8051 processors are cheap and abundant. Chip makers use it as the go to architecture for any simple embedded processing requirements. It's slowly changing though, but ARM licensing costs are still much higher. Let's hope that in a decade or so they'll use RISC-V instead.