Pelosi has been in congress since the 80s. I do not think congress-critters will support higher ethical standards that prohibit them from profiting off of insider information if they think that means putting themselves in a straight-jacket for the rest of their lives. The ability to profit off insider information is probably a reason some of our congress-critters stay in office rather than retiring and pursuing goals elsewhere.
Through the 80s and 90s, I recall politicians and talking heads using the phrase "...even the appearance of impropriety". I'm tempted to conclude there's something telling about the way this quaint phrase seems to have disappeared.
EDIT: not saying term limits are the answer, just that I can see the relationship suggested.