I'm always happy to get more free content and new heroes are great. What I would really like to see are some new maps though.
The game's director Jeff Kaplan came on the Blizzard forums to address the fan's displeasure about the fact that Summer Loot items can't be purchased with in game currency.
http://us.battle.net/forums/en/overwatch/topic/20747905428?page=7#post-134
Should the summer skins have been available with in game currency? Probably. As usual I think gamers are going way overboard with their reactions though. People who have been playing the game for months are asking for a refund because they won't be able to get every skin. These are cosmetic skins we are talking about. They have no impact on the actual gameplay.
I do think some of the skins are cool and I would like to get them myself. I also think the loot box system needs an overhaul. I have been playing Overwatch regularly since day one and I still don't have a single skin for D.Va, who happens to be one of my favorite heroes. I have had way to many loot boxes provide me with 4 sprays and not a single skin. There are a few D.Va skins I would really like to have. At the same time I wouldn't say that playing with the default D.Va skin has hurt my enjoyment of the game at all.
So yeah, I would like to see improvements but unless they go the CS:GO route I don't see myself actually getting mad about the loot box system. This is another non-free to play game that has a loot box system. In CS:GO you have to use real money to buy keys if you want to open the loot boxes you earn from playing.
They also create artificial scarcity so they can drive up the prices of their skins in the real money Steam community market. The first page of the most popular items in the community market on Steam are all CS:GO items except for one Dota 2 card pack. These skins are the most purchased items in the market and they range from $4.66 to $28.72. The rarest skins are listed for over $400. If Valve can get away with this system in their two most popular games (Dota 2 and CS:GO) Blizzard could have too.