You're forgetting the battlefield series numbering. It didn't start at "Battlefield 1", it was "Battlefield 1942"
1942
Vietnam
2
2142
Bad Company
Bad Company 2 (Which also had a Vietnam title, but as an expansion)
3
4
1
Plus a few other sort of minor titles in there for good mix.
Remember kids, counting is apparently hard.
I think it was a great choice. 1 implying that it is a prequel to bf1942 and that it is WW1.
2142 was my favourite since 1942.
2 was jet whoring,
3+4 were good but basically the same and ruined by server mods / OTT unlocking + DLC.
BC2 didn't have prone (or 64 players i think), I liked it a lot but it really felt like a different game.
I want this but I don't want to pay 50 euros.