(found the links. XP)
Their response is not incorrect but does not tell the whole story.
http://nexus.leagueoflegends.com/2016/12/ask-riot-the-future-of-the-client-update/
"When we first began work on the client update, we had to decide what order to build things in. Some features naturally fell to the bottom of the list based on data we gather about which client features players actually use. The features at the bottom of this list were public chat and the item set creator tool.
Those features likely won’t make it into the client during the beta, but that doesn’t mean we’re ruling out working on the features at some point in the future. Some players really like public chat and the item set creator, so it would make sense to rebuild them (or some improved replacement for them) in the future. All we’re saying now is that we can’t let those two minor features hold us in the beta."
"So, here’s your update on item sets and public chat: We can’t yet officially commit to rebuilding them because we haven’t finished the client beta. It just wouldn’t be wise to promise those features without actually having developers assigned to the task of creating them."
http://na.leagueoflegends.com/en/news/game-updates/features/client-open-beta-update-1
"4. Some of the legacy client's features haven't been added yet, but they're coming.
We have to rebuild every existing client feature for the client update, so the big challenge for us is deciding what order to build things in. Here's the full list of missing legacy client features, with current estimates for when they'll arrive in the beta client. Note that these features can easily be delayed past the given patch (that's game development for ya).
THE ROTATING GAME MODE QUEUE - coming with 6.24
SPECTATE FRIENDS - coming with 6.24
GIFTING - coming with 6.24
ACCOUNT TRANSFERS - coming with 6.24
BOTS IN CUSTOM GAMES - planned for 7.1
BATTLE BOOSTS IN ARAM - coming before open beta ends
CAREER RANKED STATS ON THE PROFILE PAGE - likely to slip past open beta
PUBLIC CHAT ROOMS - likely to slip past open beta
ITEM SET CREATOR TOOL - likely to slip past open beta
We've heard a lot of questions about the final three features on this list (profile page career ranked stats, public chat rooms, and item set creator tool), and we agree that each of these features is important and valuable. To be fully transparent, we just haven't yet assigned a dev team to work on them, since the devs are all busy building other aspects of the client and making sure they run well. So, it's likely that these features will slip past the open beta before we rebuild them. We'll keep you updated when we can talk more confidently about these features—in the meantime, just know that we've heard players requests for them and are working on figuring it out. "