But I can't help noticing that a large number of people us "pen names" when entering their opinion about really harmless subjects.  Why would one do this?  I have never used a fake name, why would one want to?
I noticed for example that people expressing opinions about the safety of medical records either used fake names or have never submitted a review.  Why?

Without your last name or address, to anyone other than a Hooker you've seen, you're  another alias lost in obscurity, not the famous Joe I know.  
   
   Seriously, as a Dr. you surely have noticed, some people are shy when there is no need and other people never miss a chance to ignite  controversy, or another free turn to push  buttons.  

so why did your companion rose become a call girl and write that diary?

She's my favourite.  Maybe she'll be back

you should know, you're the doctor lol!

Go ahead and tell us your last name. Everybody here is already using an alias regardless. Unless of course they are dumb enough to use their real name. That makes me think of Mr. T "I pity the fool".

We are all using aliases so why do people comment using further obfuscation?.  I have for more than a decade always been know by dr. joe, why would I ever enter a comment using another names since only my friends here and some lovely providers know who I really am.  It is like playing a character but afraid to be that character in front of others except when you review someone

We are all under cover so why cover the cover?

And do a search on this issue if you're really interested in it.  Because it's been discussed many times.  Bottom line: while it's true some aliases are used to flame and make mischief, there are many, many legitimate reasons to use an alias.  And broad-brush condemnation of them is simply ignorant.  Again, do a search.
And, as for handles being sacrosanct, are you aware there are people who have a whole host of handles tied to fake IP addresses?  They use these handles to make mischief as well.  The only difference between those handles and the aliases you scorn is you just don't know about them.
People who simply condemn aliases are simply showing their naivete.