Many of the AI companies do train and release models dedicated at one task.
I mainly use mistral, so that's my reference, but I know anthropic et.al have similar models around.
Codestral is rediculously bad at conversation, but it's -for me- the best model around for "magic autocomplete". It's also pretty good at "one shot" prompt+context generations, e.g. to make "git commit log entries".
Document.AI is unusable bad in a conversation style, but really good when wired up to a simple pipeline as "replacement" for OCR or for indexing "meaning" from documents (I'm experimenting with it for my administration, to get invoices, contracts etc into a search tool).
I presume there are many others like it.
So, what you describe, is already in place. I guess mostly the "interfaces" are missing for you, or hard to discover maybe?
For example, a dedicated model with tool I'd like, is some "shell" -a zsh or bash fork or some wrapper- backed with a dedicated model, trained for "commandline interaction".
Where instead of "git commit --fixup=[opens another terminal to git log the relevant entry]", we can "git fixup the commit that fixes full names" or "ffmpeg convert some.mov to mp4 without sound but keep quality and ratio etc". Or "run any valid tar command - you have ten seconds".
I'm now using the way too heavy "devstral" for these tasks. I don't need it reasoning, conversing, apologising. I need it translating my requests into commands, then showing these to me so I can deny/allow/whitelist/blacklist them and then run them - to interpret *and show me* errors and suggest improvements or fixes etc.
Same for - indeed - translation, writing draft mails, reading documents, etc: I don't need to converse with it. I want to have buttons, shortcuts, "tab complete" etc that's "smart" enough to understand what I need and want, preferably tunable by editing "system prompts" or such and then get out of my way.
I think the company that figures this out for my IDE will win the competition-race of "AI coding tools".
Just today, I found, zed presented a button "git conflict found, resolve with AI" . When pressed, it did start a conversational thread, but its a step in the right direction.