I love being teased and find ladies wearing skirts / dresses without panties extremely erotic.  If I am to articulate why, I think it implies the lady is uninhibited and confident in her sexuality (such that she is taking the lead in seduction - it is more psychological than physical).  

Me, not so much.  If I make a wardrobe request at all it's usually for street clothes...something that she might wear to go out and have drinks with a friend.  And I'm definitely with you on pantyless...when the clothes begin to come off and there's nothing underneath? That totally does it for me.

Absolutely. That is very sexy.

...to not wear panties. None have ever mentioned that it's a request they don't often get. I once asked a lady to wear the crotchless panties she had on in a photo on her site. She did wear them but commented that it was the first time she'd worn panties for me. Do crotchless panties count?

Than a gal in a long loose dress or skirt with no panties.  Flip up the skirts and go to town.  Hot!  A neighbor of mine seduced me that way once.  She opened the door and lifted her dress to show me her snatch.  10 minutes later we were in her apt fucking like bunnies.  Ah memories!

...if it wasn't very common. Also, I wouldn't ever think of a gentleman as "weird" for pretty much any request...we've all got preferences, simple as that. Be you!

Pantyless fantasy / request - is it uncommon?  

Once, when I was traveling, a gal showed up at my hotel room wearing stretch pants with no panties underneath. I thought it was so as not to show panty lines, but she assured me she never wears undies.  (She does wear a bra though to harness her enormous tits.)

I get this request often enough to think it common.  But then again, I do have a furry bush that many are mesmerized by, and I can understand how the panties just get in the way.  

I sometimes go commando under work out gear or under a sundress very liberating and exciting.
So when I get a request for it I am wet before he arrives at the door

I enjoy seeing ladies going commando in a cocktail dress.