I think most experienced SU users agree that the change of name from Layers to Tags was very worthwhile. It avoids confusion and makes it clearer that they are simply attributes that affect visibility/appearance.
When you create a Component, a dialog box pops up inviting you to rename it from a suggested default and optionally to set other attributes. Would it be handy for this dialog box to enable direct tagging in much the same way as Entity Info? There might be a box immediately under the Definition one to allow you to do this.
I see it working the same way as in Entity Info but with slight differences. Instead of having Untagged as the default option, you would have something like “Tag1” or “DefaultTag”. If these tags do not already exist, Sketchup will create them if you don’t overwrite them. If you overwrite them with a new tag, again SU will create it (just as Entity Info does). And if you start typing something that does exist, a filtered list would appear with just the matching Tags for you to choose from. If you go on typing, the options diminish until SU understands that you are making a unique Tag. Or you just choose from the whole list by using the usual drop down arrow.
I realize that most experienced users will already have an established workflow that means they are used to doing this as a two part operation, ie. create and name component, close dialog box, then assign to tag via Entity Info. But I would argue that we should always be looking at ways to make things easier and more logical for newbies as they are the future. It seems to me that encouraging people to name and tag components before they do anything else would be valuable. The current system makes it too easy to forget the tagging.
Some might argue that this suggestion risks bloating the Component dialog box and is messy because it creates two ways of doing the same thing. Maybe a way of addressing that is to have the Entity Info dialog box itself expand to create the Component dialog box.
Incidentally, having smart filtering in the tag box here and/or in Entity Info might prevent that annoying problem many of us have when we find we have inadvertently created a new layer called “x” or some such.