For what I can see in the Twitter video, this new app will be useful because you could open channels directly from your cold storage wallet with just a small fee and 1 tx fees.

Let say you used up your channel balance but you have some Bitcoin in cold storage you can rebalance your channel with just one on-chain tx and a small fee to ACINQ for opening the channel. That could save you some serious money if btc tx on-chain get too expensive. It also makes Lightning a lit easier for the average person.

I guess we will see once it becomes available to download.