I agree that the use of tags for bold, itlaics and underline is strange.
Suggestion, if you are comfortable editing html and need more power than the design editor provide, may I suggest you take a look at Ultra Edit. Very powerful editor, 45 day trial and inexpensive. I use it to edit topics outside of RH. For example, you can find all instances of <b span style ect> across ALL topics and simply make them <b>s .
It is my understanding the 3Wc has "depecated" the <b><i> and <u> tags thus encouraging develpers to use more elaborate tags for produce font effects.
Hope this suggestion helps your efforts!
<b>,<i>,<small>, etc are not (yet) decaprated in HTML and XHTML F,T,S. See http://www.w3schools.com/tags/tag_font_style.asp, although I think that it's sensible to avoid these tags altogeher.
My solution to this untide HTML is avoid inline styling and above mentiond tags altogeher. Personally, I use span classes for every use, even though separate uses have the same styling, such as field names, page names, paramaters, etc. By creating a separate class for every use, you insure that you can easily change the style of a specific type.
This means ofcourse a rather large style sheet and you cannot use the styling options in RoboHelp itself. But once you're used to that, it actually saves you a lot of time. I've had to change some specific styles more than once and it's much easier to to change a style sheet, than change hundreds of topics with a Find and Replace or by hand.