They did not know that the bravery bonus would no longer be there or that VIPs would be getting 1000TP a month for a few months when they downgraded from VIP/chose premium over VIP 6 months ago, or that it would only cost $10 per month to subscribe and that VIPs would be able to unlock elite and not just hard if they downgraded/chose to go premium over a year ago. The choices they made to downgrade were based on the options that were there at the time.
Sure they can opt to return to VIP, or to start subscribing for those that chose premium initially, but after buying most every VIP perk outright for the life of this game, subscribing so just to be able to open on elite and get access to the bravery bonus is not something most premiums will want to do.
Likewise it leaves a bad taste in every premium's mouth and devalues their choice to not sub or stop subbing each time the VIP package is improved. Turbine has added the ability to open on elite, made the subscription deal cheaper, gave VIPs more free TP per month, and now are going to give them an effectively exclusive exp bonus.
While subscribers have gotten more and more as their subscription price dropped by a third, all premiums have gotten was a way overpriced single use elite unlock they have to pay extra for.