Mega Drive Ultimate Collection arcade unlockables revealed

Sega Europe have posted on their blog all the arcade titles that will be unlockable on Mega Drive Ultimate Collection. I was rather disappointed by them as I was expecting more sprite-scalers, but these are definitely an added bonus. Here they are:

1. Zaxxon, 1982
2. Congo Bongo, 1982
3. Fantasy Zone, 1985
4. Space Harrier, 1985
5. Alien Syndrome, 1986
6. Shinobi, 1987
7. Altered Beast, 1988

The fact that some of these games have their Mega Drive counterparts also on the disc makes them less exciting. Why not keep the arcade versions and replace the Mega Drive ones?