While this does help for traction on playability for cards to create teams it’s really a bad idea for collecting. By combining you decrease the value of betas and increase the value of alphas.
I’d put peoples complains aside and just allow users to either purchase singles to level them or sell them in the open market to obtain betas. I think by combining both into betas you’re de-valuing the cards economy. Logically alphas combined will go up in value and betas become even more common.
Personally you cry babies with unleveled alphas should suck it up and combine the cards the normal way or trade/sell your alphas to betas...