“Huge/Large/Super pages” (https://wiki.debian.org/Hugepages) exist because the typical 4kB pages have too much overhead in programs that allocate lots of memory.

So, sizing pages down to malloc-sized blocks will impact performance, even ignoring the fact that, to have true bounds checking, pointers will have to carry size information, making them larger (64-bit pointers have quite a few unused bits on typical systems, so it may be possible to hide that somewhat.

Also, if you truly want to do bounds-checking, you will have to create a ‘page’ for every element of every array (either up front or on demand), and, if such elements have structure, for each part of the structure.

Huge pages mainly exist to alleviate TLB pressure and page fault latency. But that performance penalty is tiny compared to the alternative of in-program bounds checking that we currently use.

Similarly, pointers don't necessarily need to be changed and your array problem isn't valid. Cachelines could be marked with canaries that fault on read/write, similar to how the NX bit currently works.

The NX bit is actually a good example of a hardware security-performance trade off that nearly everyone agrees on. Now 20 years later, we can afford to mark several more bits at some cache offset for a hardware bounds field.

Programming in a language other than C++ sometimes feels like putting training wheels on a Ducati and driving 30mph down the freeway. And if you know what you are doing in modern C++, the memory is much easier to deal with. You can do anything and more modern iterations of the language add some nice updates to the syntax sugar. It is rather dense to get your head around it, but once you do it is like writing poetry. I like the idea of just making the hardware safer, is there any downside to that?

This is broadly how Intel memory segments were supposed to work.

The 8086 did not check bounds, so nobody bothered using them, and when the 80286 came out that could check, everybody disabled that feature and used it as a faster 8086.

Probably too many key programs played too many tricks assuming a flat memory model that this was never going to fly.