Personally I don't see any issue with using someones idea, well, aslong as it is not an exact copy in every sense.
The creation of the mod is what counts, doing the work to achieve the results. Two people who do the same mod idea will reach different conclusions and use different techniques to achieve it.
Mods are all based on inspiration from other games and mods.
Someone offered others to put their money where their mouth was and show what original content they had created, well these three mods of mine I consider to be unique and I have not seen anything like them yet. I mentioned them in the forum at one time or another during development and I would not be bothered at all if someone has already made mods like them before I released mine. Share and share alike. I came up with the ideas my self, well almost as some I got inspiration from other games.
http://www.tesnexus.com/downloads/file.php?id=26218 < This was a unique idea of mine.
http://www.tesnexus.com/downloads/file.php?id=31195 < I don't have horse armour so this is a cheap mans alternative with an extra perk, it is kind of original with obvious inspiration

http://www.tesnexus.com/downloads/file.php?id=31215 < My inspiration was Fable when you can buy and rent houses.
All code I used in scripts is purely my own work. I gave credit to someone who gave me some visuals that I am unable to make my self yet (some extra butterflies). I did however look at other peoples mods when trying to do certain things to see how others had done them, but I did not "copy and paste" code, I merely looked at their technique and then altered it to suit my needs; I consider it research.