And stuff like Akira/Rurouni Kenshin Tsuiokuhen (which is done by DEEN btw) also came out some years before Excel Saga/Mai Hime yet also look remarkably better than those shows.
I was more referring to how anime overall was watched around 2008 and unless you had the DVDs, you couldn't really tell the real quality of the anime anyway since you were experiencing it through a crappy 360p online stream for pretty much every show. During that time, Deen's animation didn't really stand out that badly as opposed to nowadays.
There were also plenty of other low effort VN adaptations during that period.