Idle temps are meaningless for the most part, and you can throw out pre-conceived notions when dealing with Ryzens. They aren't Intel and don't work like Intel.
At idle, Intel cpu's cut frequency and its power requirements down across all the cores which lowers temps over the entire cpu, but all the cores remain active to some small degree. So windows/background tasks are split up amongst all the cores and you'll get the occasional spike upto mid 50's, generally staying around low 30's.
At idle with Ryzen, amd shuts down entire cores, leaving only one or two active and the whole workload of windows/background tasks is on that one/two cores. So only they are active, with a higher % load than any one Intel core, so temps will be slightly higher, and more consistent. You'll get a more solid block of 50°C instead of the Intel spikes.
So your idle temps are perfectly normal for Ryzen, it's only 1 or 2 cores, loads will activate the remaining cores into use, so don't affect the cpu to as high a degree, they've got to get to the idle active core temp first.
60°C gaming, not too shabby at all. 90°C under stress, well that's a little much, but unless you are into serious cpu load programs like rendering, content creation, video editing and compiling, then you'll likely not ever see such cpu usage. So figure your worst cpu gaming will be between @ 70-80°C. Which still isn't bad.
Upgrade cooler? Sure, go for it. You can't over-cool a cpu, but sure can under-cool one. The stock amd Wraiths are very decent for what they are, stock, but you can always do better.
The Gammax 400 is better than the 300, which while better than the Wraith, isn't performance worth paying for, not enough of a difference except for sound volume. The 400 is eminently better suited all around.