I agree with both of you here's why, are the MW2 maps bad not in my opinion. Are they better than MW19 maps hell yes.
Everyone slags Vanguard. Now the maps on that game were ok, some good and some bad. They launched with 16 yes 16 6v6 maps.
Cold War maps felt like the old school 3 Lane back in the day maps.
Vanguard and Cold War didn't suffer from the curse of Warzone map design for MP.
They didn't want Treyarchs goofy yet fun and colourful maps, nor did they want Sledgehammers WW2 stuff in their Warzone.
The recent Modern Warfares suffered from this building a big map, and cutting bits down and scaling it down for MP.
6v6 map design is essentially a by product or leftovers if you would of Warzone.
Now are MW2s maps as good as the OG MW2, BO1, BO2, MW3? Most definitely not. I don't think they are all that bad tho.