I don’t mind ~/.* for config, especially when the config is just one or two files. What I don’t like is programs like go and cargo treating my $HOME as a dumping ground for every file they want to download and/or cache.
And if you install more than one version of go, they get placed in $HOME/sdk [0]. Last I checked, this path is hard-coded with no override, despite this being a known issue for 8 years.
/tmp must be world-writable and for multi-user or multi-tenant systems it becomes a security hole. Storing temporary files in the current user's home directory (or a subdirectory thereof) makes sense.
What doesn't make sense is this blog post about TMP and TEMP, and ending with "I don't know why" (in different words).
The reason is simple: different programmers thought the other name was bad. They were under no obligation to come to a consensus.
Don't forget about TEMPDIR and TMPDIR! Also Windows has its own environment variables for this. But generally, Linux software ported to Windows still use TMP or TEMP.
It makes sense when it's a user option. If /tmp isn't an option due to security concerns, then use $CWD by default. I can always alter the config to some other location if I do not like it. With the amount of programs that litter $HOME, especially with caches, you have to whitelist directories when backing it up. With a naive rsync, you'll find half your transfer is junk.