I feel that the warforged would be out of place in a default fantasy setting, especially the currently implied one for 4e. I feel kind of the same about the already confirmed tiefling, but much less after thinking it over for a while. For me, the warforged is the "could be worse" in regard to the appearance of the tiefling.
A particular thing that worries me is that these radically different races seem to immediately attract new players attentions to the point that they are just playing a party of freaks. It happened to me in a FR campaign I ran once, and sure I could rule 0 against it, but I couldn't argue with the players and ruin the game, so we ended up a bunch of planetouched and a drow. Imagine this group waltzing heroically into their first generic small village, not to mention how the heck they all met each other... Now imagine having a warforged with them.
A particular thing that worries me is that these radically different races seem to immediately attract new players attentions to the point that they are just playing a party of freaks. It happened to me in a FR campaign I ran once, and sure I could rule 0 against it, but I couldn't argue with the players and ruin the game, so we ended up a bunch of planetouched and a drow. Imagine this group waltzing heroically into their first generic small village, not to mention how the heck they all met each other... Now imagine having a warforged with them.