I intentionally dropped a lot of those, to have the editor focus on speed and clean usability.
The new editor has a document importer, meaning if you create your question in Word, or Writer, and copy it, it will also copy the formatting.

I am open for input, but in my opinion especially new users tend to be overwhelmed by the enourmous editor we had in the old version.

I thought that the policy was not to remove any features, but to make them optional (basic vs. advanced mode) instead.

For new users you are right, but I fear that old users will complain about a limited text editor. Having to use an external software for text editing is not very user friendly in my eyes.

Any decision on that?
Copy and past from word processor is no feasible alternative in my eyes.

We have made a decision in the development team to have underline font size and font color added. (The latter two will cause problems for sure)
After some research, we found that the industry standard is a very light editor. Most other comparable solutions don't even add a fontsize or fontcolor option.
The focus of LimeSurvey 4 is an easier to use user interface and the editor is one of the reasons a lot of customers are overwhelmed, as it is enourmously overcrowded in functionality.
If advanced editing capabilities are necessary, I'm sure it can be done via either copying from an external text editor, or even in html.
Working with an external editor is not bad UX by the way. On the contrary, it is an anti-pattern in UX-Design to have every possible use case reflected in an interface, since most of the users will never need anything that is more than bold, italic, and link, if at all that much.

A pro mode with more options is probably possible, but the discussion will be postponed to an undefined time in the future.
Ticket resolved for now.

If all HTML tag work, it's great. I tested <u>...</u> in RC6 but the tag was just ignored ...

Fixed in Release 4.0.0-RC7+191111