Even if you do so, the program size is still bigger, and it consumes more disk, RAM and most importantly cache space. Wasting cache for having multiple instructions when on another architecture it's done by only one doesn't make particular sense to me.
Also, it's said that x86 is bad because the instructions are then reorganized and translated inside the CPU. But it seems that you are proposing the same, the CPU that preprocessed the instructions and fuses some into a single one (the opposite that x86 does). Ad that point, it seems to me that what x86 does makes more sense: have a ton of instruction (and thus smaller programs and thus more code that can fit in cache) and split them, rather than having a ton of instructions (and waste cache space) for then the CPU to combine them into a single one (a thing that a compiler can also do).
x86 also does macro fusion. Difference is RISC-V was designed for compressed instruction and fusion from the get go. X86 bolted this on.
Anyway what you gain from this is a very simple ISA, which helps tool writers, those who implement hardware as well in academia for teaching and research.
How does the insanely complex x86 instructions help anyone?
IME icache misses are a frequent bottleneck. There's plenty code where all the time is spent in one tight inner loop and thus the icache is not a constraint, but there's also a lot of cases with a much flatter profile. Where icache misses suddenly become a serious constraint.
Depends on the application. But even if they are few, it's not a good reason to have them just for having a nice instruction set, that if you are not writing assembly by hand (and nobody does these days) doesn't give you any benefit.
Also don't reason with the desktop or server use case in mind, where you have TB of disk and code size doesn't matter. RISC-V is meant to be used also for embedded systems (in fact their use nowadays is only for these systems), where usually code size matter more than performance (i.e. you typically compile with -Os). In these situations more instructions means more flash space wasted, meaning you can fit less code.
> that if you are not writing assembly by hand (and nobody does these days) doesn't give you any benefit.
An elegant architecture is easier to reason about. Compilers will make fewer wrong decisions, fewer bugs will be introduced, and fewer workarounds will need to be implemented. An architecture that's simple to reason about is an invaluable asset.
Also, it's said that x86 is bad because the instructions are then reorganized and translated inside the CPU. But it seems that you are proposing the same, the CPU that preprocessed the instructions and fuses some into a single one (the opposite that x86 does). Ad that point, it seems to me that what x86 does makes more sense: have a ton of instruction (and thus smaller programs and thus more code that can fit in cache) and split them, rather than having a ton of instructions (and waste cache space) for then the CPU to combine them into a single one (a thing that a compiler can also do).