A few players have said on these forums that in DDO monks do in fact need Combat Expertise (and thus 13int and dex) to get improved trip.
That claim of course differs from PnP where monks can take improved trip as a bonus feat at level 6 regardless of whether they meet the requirements or not.
So the question is: has anyone actually verified that monks can't get improved trip at level 6 without the usual requirements, or is this more of an educated guess based on Turbine giving us more bonus feats and them being available at levels that vary from those stated in PnP?