I have played computer games for years but have not played MMOs very much. It seems to me that they all suffer from a similar flaw.
A big problem with massive online games has always been forming compatible groups at random. Such groupings range from terrific to terrible with the average being somewhat tedious. Anti-social players that cheat others make for terrible groups but even when all players are honest and sociable they still play at different speeds. A few naturally adventure about as fast as grass grows but others like to move along at point five past lightspeed. These speed differences frustrate many players and causes many to adventure alone or avoid MMOs entirely.
"AD&D Neverwinter Nights" first went online 22 years ago but it, and no MMORPG since then, seems to have solved the problem of speed compatibility in groups.
How can group matching in DDO be improved?