Here I come with my hilarious idea :-D
It would be nice if grangers could use the HOVELS AS TELEPORT gates. In this case maximum 3 (but for simplicity let's say just TWO) could be built, but when entering, the granger would appear IN the other one (exiting still needed, so she is able to hide there).
This could be a nice escape route on small maps, and to make a quick access to outposts trough enemy lines.
Generally alien outposts at S3 near human bases are making the base destruction quicker (what is the flattest part of the game anyway), but for the humans destroying them is slowing down the alien spawning and allows them to quickly raid the OM+her eggs who lacks the defense power what was transported to the outpost.
So it's just an inspiration for grangers to make wider bases and to travel safely when risky situations are happening, not to mention to give some reason for this worthless structure.
This could be a totally new function and I guess it's extremely easy to apply, while it woud not change the balance.
Otherwise I don'T think that if one hovel is useless, then 2 or unlimited would turn them neat :-)