The main reason is we don't want to update all skins when we add features like the visibility badges and things like that.

Can you give an example of styling that you find hard to override?

Most anything in sitewide-style.css which is mostly sitewide-header - our main menu - first thing visitors see

In v6, that sitewide-header gets styled from 2-3 different css files I believe. (background-color)

Adding custom style in collection >> settings >> advanced didn't seem to have any affect

Looks like some of that will change for v7 though and be done in the backend. At least for some of the standard bootstrap skins but not all as of yet. Bootstrap Manual for instance.

Likewise for table and related elements. I think that might have been coming from rsc/bootstrap/bootstrap.css or bootstrap.min.css

Yes, I want to style basic stuff like tables, input etc and also the main menu aka sitewide-header as it is visually prominent. They can look odd depending on the chosen skin and any styling changes made to it. I think it would be best if the skin styled every element in the collection with a few exceptions of course for items that are truly system items or things that get styled by a plugin.

An option to style the sitewide-header in one place or maybe a way to copy style from one collection to another with a click or two.

The freedom to easily choose what items to put in that menu would be nice as well.

I see in the latest version, 6.10.7, that this

 .sitewide_header {
    background: none; /* Removes Gradient */
    background-color: #41406b; /* Replaces Gradient with Solid Color */
}

added to Collection >> Settings >> Advanced >> Custom meta tag/css section; works well now and changes the background-color for the entire sitewide-header whereas before, "This Site", other menu items and the blank area were styled as three different css elements and in different css files.

Thank you.