Mars was a great drama, I wouldn't want a remake no matter the leads. The chemistry between Barbie and Vic can't be recreated - not to mention the fact that they were a couple at the time and it's evident in all their interactions. I agree that re-making a drama which was very good in the original is never a good idea.
On my part I much preferred Ikemen to You're Beautiful, but that's me and I didn't think the original to be a particularly good product, just a display of eye candies, so I personally count this one as an example of a good remake of a mediocre drama - again, please don't hit me. Akai has already done so, she'll be lenient this time, I hope ;)
Therefore, I'm all for remakes of things which were not good enough in the original and can be vastly improved. :)