I miss those days where I could go into Twisted Treeline and not have to worry about AFKs or OP champs taking the lead. Its basically easier to kill them (except Illaoi who can dominate every squishy, unmobile champs).
I miss those days that people would play Dominion. It takes forever now to play a 15 minute match (at best). Its a lot funner than Summoner's Rift right now.
I miss when ARAM allowed the whole champ select... wait, we're still trying to tell Riot that this is how ARAM should be.
I miss the other ARAM map. Riot put so much effort into it.
I miss Showdown. It lasted at most 5 minutes and best of all, no team fights. Solos and Duos can have a blast here.
I miss how URF actually "balanced" certain champs so they couldn't spam and be played the most and make games less fun for others. (Like Nidalee and Hecarim)
I miss Team Builder.... If it takes half of the player base from the new mode, there is a good reason why it is. Half the player base probably doesn't like being forced into a random area. If I wanted to play Draft, I would play Draft.
I miss the original Mordekaiser. He had a better chance of being a bottom lane marksman than he does now. More MS, ranged Q, a better E, and a not broken passive or ultimate.
I miss the mana stuff. Specifically, I miss the
spell.
I miss the contests Riot use to give us, like comics or artwork. We didn't even get a contest like Brazil did for those icons.
I miss how Riot use to give us icons for IP. About 15 so far we could have had for IP. The poro icons for the christmas event are debatable though.
I miss the fact that Ao Shin was going to be a champion last year.
I miss being able to play duo top, all mid, three mid/bot/top, or do whatever. Its too far into the meta, we don't even get a Sandbox mode. Its all basically in "speculation" and we only had a few discussions on it.
I miss feeling like getting champions was easy and would only take about 1 to 2 years... working on year 3 and I'm still not caught up with other players.
That's what I miss...