The reasons why Bright are keen to leave the O&K (as per the Chronicle article) make perfect sense.
But, if this has been in the wings for a while it may have stemmed from "Akermania" & Bright not getting a home game over Easter in 2011 as a result. Bright were understandably really dirty on the league because an Easter fixture brings their club valuable tourist dollars. They felt in all the hype to bring Aker to town they were neglected. In addition to the Milawa/Tarra game, from memory I think a game was also played between King Valley & Tatong to which bugger all people showed up. So the opportunity was lost.
I don't think it has anything to do with Easter. Basically they have six footy sides (u12, 14, 16, 18, res and seniors) playing in four separate leagues (MDJFL, WDJFL, O&K thirds & O&K). They have been talking about going to the TDFL for a few years now - it was definitely discussed when the BDFL sides came in, mostly because of the travel. But now the option of playing u12, 14, 17, res and seniors all on the same day at the same ground in the TDFL is the main kicker.