It's not just about seats, there's comfort too (they have advertised having extra legroom and the 180s do not have as much! Also, wireless - has that been done in 180s? are there any issues there?) but also they want a restaurant on certain services, which the 180s can't provide.
OK, the restaurant can't work (but, to be fair, if it were on the right services, it wouldn't be needed. A cafe bar a la NXEC providing sandwiches and toasties would do just fine). But would/could GC not referbish the trains and, in theory, put fewer seats in with greater legroom?