Freeview also made technical changes
It increased the interference robustness (at the cost of reduced bandwidth per multiplex). I can't remember if it switched to 8K mode from 2K mode or if that came later. That change also improved signal robustness but meant that the original STBs and TVs would no longer work.
Dodgy signal in many areas and suceptibility to impulsive interference (greatly improved by 8K mode) were major issues for On/ITV Digital so in addition to the free message this really helped.