''I think for thr A321 V1 is about 135 and VR about 145 kts.''
Think again. Add about 25 to those figures for something more realistic and typical operating weights. The A321 is at about the limit of the type's design parameters. One of my colleagues did the design work on the 321 flaps and it was a nightmare to get more lift out of a wing that's already too small for the aircraft. Any increase in mass over the 321 will need a major redesign and a new wing - and possibly a lot of recertification.