Because maybe you didn't need that second Domestic Sleepers.

Maybe bioroids really are Stronger Together (and high strength sentries are something people aren't playing enough of).

Maybe the low credit cost is compatible with your PE deck's relative lack of cash.

Or maybe you just like to play fast and mean.

Ken loves Donut. He has the influence for him. He recoups the penalty on his first run event per turn. With Account Siphon in faction, he can create credit swings that are harder for the corp to recover from with operations.

Other resource heavy criminals might enjoy installing him for free with Career Fair.

Expect Donut and Sunny Lebeaux to be friends too. She's gonna be packing nothing but resources and programs.

I completely disagree about Ken. Why play a card that hurts the cards that work well with your ID?!? Play it in Whizzard, where it puts the Corp in the awkward position of having bad asset economy and bad operation economy. —

This asset is great for baiting runs because the asset is still useful if they don't take the bait. A fully stacked install-advance-advance/runner turn/advance-advance-trigger will net you 12 credits profit for 6 clicks and one card. The downside is that you might find yourself wishing you scored an agenda in that window instead, so you really want to be able to convert those credits into a scoring window (with Ash, SanSans) or taxing ice installs the turn after. If they succeed in running and trashing it, make sure the run was more taxing for them than for you too. Requires more investment than Melange Mining Corp but can net more profit the turn after installation (barring Biotic Labour installs). If you have a Trick of Light to spare and would rather have money than an FA-ed agenda (because things are going rough) Weyland can pump this card up in a pinch. Mushin No Shinning is also and option in shell Jinteki, creating a potential 21 credit net profit after 2 turns (although these decks are typically operated on the cheap).

For one point of reference I look at Thomas Haas may serve a similar role in baiting a run. As a Mushin target I'd feel much better laying Thomas as he'll be able to trash himself if the runner does choose to access him. GRNDL Refinery strikes me as something you want to give at least a little more though in protecting only because it is so easily trashed if accessed. Of course there's a huge difference in credits between the two cards but if you're looking to just bluff the runner Thomas may be a better choice. —
No it doesn't make any sense to Mushin Thomas Haas, since Mushin specifically says the cards can't be scored or rezzed until the start of your next turn. —
Probably goes without saying, but GRNDL is a great asset in Gagarin Deep Space decks, especially supplementing PAD Campaigns. They need to get rid of the PAD's, but that costs 5. They simply **can't** let you score a 4/2 or over advanced Atlas, so they will check your "install-advance" servers relentlessly. More often than not, they'll trash the GRNDL Refinery and be juuuust too poor to trash your PAD Campaign :) —
I would say less useful as a bluff than as a "test the waters" card. If the runner goes for it, no major loss, but if they don't, they may have trouble getting their rig set up or simply be focused elsewhere. In which case, as the OP said, just take the cash and move straight on into an agenda. —