HP to buy Iso

I've always found it strange that when spending money on the game I have to choose between HP and Iso.

Personally (and I'm sure if people agree/disagree they will say) It would make more sense if HP is the ingame currency, to use that to purchase Iso.

So if I'm missing a cover or 2 to max out a hero and want to get the Iso too, I don't have to make 2 purchases.

Also means that when I purchase HP, I know I can spend it on whatever I need.

It might only be a small change but I just think it would make things a bit easier for a lot of us.