Why are some rewards unavailable for Coop vs. AI players?

Mikichu, Player Support Specialist, advised me to post here, after he answered my support ticket. Since this is the only way my question will reach the Riot Developers.

In the support ticket, I asked why Coop vs. AI players are excluded from receiving certain rewards, most recently the summoner's icons that come with the release of the Summoner's Rift graphical update. I'll quote what I wrote in my support ticket;

Hello support,

It's not the first time Coop players are left out with special events like this, and I'd like to know why.

I have tried normal and team builder games on Summoner's Rift, but it was a negative experience for me. I've had too much toxicity and negativity in my games, and my win-loss-ratio is so terribly low that I've lost faith in the matchmaker system. This is why I only play Coop games, which are far more relaxing and enjoyable. Therefor, obtaining the icons by winning match-made games on Normal or Team-Builder queues is not an option for me. The icons are simply not worth the stress and negativity I have to face to get them.

There has been several events where Coop games were left out of any rewards. Most recently the Shurima event, but in the past also the Freljord event and One For All game mode. Additionally, a number of Summoner's Icons for the Harrowing, Snowdown Showdown and Lunar Revel were unavailable to Coop players. These are based upon real life holidays, so in my opinion, should be available to everyone.

I can understand that Coop players are left out of any end-of-season rewards.

The Summoner's Rift update is awesome. It's the biggest graphical update I've seen so far, and it's cool that you celebrate this. What I don't understand is, why Coop players can't be part of that celebration. I've played Coop games at the old map for years, so this is a major graphical update for Coop players too. Why are we left out of this celebration?

I can't help but feel like Coop players are treated like second-class players. It feels like we're not valued as much, because PvP is where all the cool kids hang out, and Coop just isn't cool enough. I can't imagine that Riot would want the Coop players to feel that way.

I'd like to receive a statement of the Riot developers of why they exclude Coop players with events like this.

Thanks in advance, Purnylla

I hope one of the developers read this and can give me a reply. Thanks in advance.