The most generous explanation I can think of for our beloved Ascaron developers is that they were stretched too thin, and too short on time, to give the game the polish it deserved. Therefore, there are many rough edges, many more than are immediately apparent, because so many of these rough edges concern coding. There's just some really poor code in there.
An example would be that they didn't seem to plan AT ALL for people playing on OS's higher than Windows XP, or on 64-bit systems, even though both were commonplace at the time Sacred 2 was made. These two things alone cause all kinds of problems.
You're hearing a lot of this memory leak information second-hand from me, as it's really dimitrius154 who did the work and told me all about the reasoning behind the changes. Some weekend after we push out this test version, I'll try to make some threads unpacking and explaining all the details he gave me. We've got a 40-page private discussion running as it is.
I would have already put up some more posts to build hype for the new CM Patch, but I have a new IT job that's taking up all my time.