When you put text on a molded part (raising or lowering it), you generally need to add a bit of draft.
If you extrude, you can add draft.. except when text is involved.
[here I just typed «TEST» in 10 point bold Arial end tried to extrude by 0.5mm with a 5º inward draft and then with a 0.01º inward draft]
There are many other issues with text (alignment, positioning, path following, performance, etc), but those are more inconvinences whereas this one creates a special kind of hell when the text is longer than a character or two. If you don't appreciate how awful that is, I encourage you to try extruding undrafted text then drafting every face by hand and then imagine it's something you have to do for about 45 characters