LEGO Ideas, as it is intended to, brings fans models that they are unlikely to get any other way. As demonstrated by 21319 Central Perk, which keeps selling out, the sets can be hard for fans to get their hands on.
Two of the sets on the list, 21309 NASA Apollo Saturn V and 21311 Voltron, are absolutely huge. The former kept selling out upon its initial release and the latter is the only chance Voltron fans are likely to have to see the set represented in the brick.
Bear in mind that this list is reported in good faith, there is always the possibility that some sets may sell out sooner or may stay in stock longer than expected. It is a useful guide though for those debating what sets to purchase during the remainder of 2019.