The thread title should be changed. The OP doesn’t read very well in the least. If you want to talk about grenades, then name it properly. Completely separate topic.
As for the maps… I blame fundamental map layout being too linear at the core with little separation between viable combat zones. Lack of side objs to distribute players. Lack of forward spawns to allow for dynamic map control. Things would be improved by greater emphasis on spawn waves and map control. More creative skill based travel opportunity. More fast-paced, creative, and just plain new obj types.
How can the current maps be improved without major changes? Well the simple installment of more contestable map-flow side objs, forward spawns, and more stable spawn waves would help most maps tremendously. However, the rest of the stuff I’d like would be more realistic in future maps.