What European DM bands do you have in mind? I'm not very well-versed in death metal, but I can say that I share 345's opinion on the genre, and that it's quite rare for me to hear a death metal song that is actually memorable, and sticks in my head after it's over.
The genre as a whole has a number of creative disadvantages. For one thing, it was founded with extremeness in mind, and the emphasis in DM songwriting and performance is typically more to 'blow away' the listener with speed, loudness, and chaos than to be diverse or memorable.
Death metal has a pretty specific formula which does not encourage experimentation, or 'straying from the norm'; such deviations often result in a backlash from fans and reviewers, as illustrated in
this Morbid Angel review, where the reviewer dismisses "Angel of Disease" as 'punk metal'.
As I said earlier, a lot of extreme metal genres focus more on creating a consistent soundscape than on creating memorable music. I understand that a lot of people here prefer their music that way. However, it's not hard to see that there's a lot less brain power involved in making music that all sounds the same than there is in making unique, memorable, and sonically-diverse music.