Yes, it is. When your intended solution may likely just create more problems than there were in the first place, it is better not to try.
Currently, at least informed people know that transaction hashes are unreliable. People who understand this are a small minority of Bitcoin users already. Now consider that you implement canonical transaction hashes, which aren't actually fully canonical. Then people rely on them because no one yet knows they aren't. Then someone figures out how to make them malleable. Kaboom.
Fair enough.
It also argues against having
The core problem, really, is that there's transaction script in the first place. This was an idiotic design decision in an otherwise brilliant protocol, and has caused nothing but grief and pain. We end up with a hobbled transaction script that can't really be used for any of the flexible purposes it was meant for, and a few hard-coded, "trusted" transaction types which don't require a script language, anyway.
Re-designing the sigScript so that it just pushes would help.
I agree that it is a pity that the scripting system was crippled.
The MAST system would have been a big improvement. You pay to a MAST hash. All the complexity is on the spending side.
To prevent people using the MAST hashes as messages, there would need to be a way to encode pruneable data too.