There's actually a very good reason for the limit.
Whereas selectors page their results from the db ensuring that there are never more than a few records in memory at one time the native SQL does not.
So the native SQL is typically much faster because of that but can have a massive memory footprint if there is no limit on the number of records that are loaded into memory.
Also since Helium is a multi-tenant system (hosting many different apps) if one app causes memory to run out on the server it will cause downtime for all apps running there.