Chances are that most webmasters will offer a recip. link anyway.
Literally 5 minutes ago i got two sites submitted to my directory and the guy had already inlcuded a link to my site in both of his links sections without me asking.
On another site though, i have a directory as a part of the site (as oppose to the whole) and i charge for listings, but offer a discount if they link back to me (i offer free listings for purely informational sites).
In this case I want to maintain quality of my listings and try to avoid mass submissions, as well as giving the webmaster a choice (and incentive) to link back to me. Charging for listings also guarentees (well, almost) that submissions will be on topic.
I'll provide a link back if you promise that your submit url button works! ;) (Sorry, still ranting)
Seriously though ... if there is a legitimate reason to link back to you, I don't think most would find it off putting. However, there have been a few cases where that particular request sent me packing. I have a links page for general guides and directories which are not "specific" to my industry but rather travel in general. I don't really mind putting a link there ... but they better have a really good and informative site as well as pretty decent PR before I will agree to do it. Otherwise, forget about it.