If you are tossing "realism" out the window, just have your shadowrunners teleport in, steal the thing, and kill everyone within a 3 block radius with one spell with zero drain. Oh, and let them wear Ghostwalker's skull as a hat while doing it.
There is "realism" (which isn't strictly the correct word choice, here) and there is "plausiblility" (which IS the word we are looking for, here). The world of Shadowrun works because of the latter, people everywhere are doing what would be plausibe, I.E. what is appropriate and makes sense for the context of their world (the Shadowrun setting).
Is it plausible that a corp would pick someone up off the street (or from a corp enclave, or what have you), spend hundreds of thousands if not millions of nuyen and 8 to 10 years of training on someone they expect to, conceiveably, take a bullet as part of their job? Does that make sense? Is it plausible?
Or does it make more sense to have someone with 6 to 12 months of specialized training, worth only tens of thousands, maybe 100,000 nuyen, give them the exact same gear as every other grunt out there so that they don't get singled out and killed before doing their job, and then put them in a position to best aid the security forces posted at a facility, even if that position is in a secure room summoning spirits and siccing them on the opposition and/or spying on them? (Sorry, long sentance.)
Setting up the opposition like a standard fantasy RPG style adventure is fine for some groups. It is fun for a while, and some groups never leave that style of play. It's a little too Pink Mohawk for me, and feels like lazy writing. I much prefer a game set up plausibly and organically, based upon what would actually work IRL (assuming magic and cyber and what-all).
There common sense rules the day, and I can expect my actions, and the actions of the opposition, to follow simple rules and chains of logic, even if they are not immediately evident. It allows me to put more faith in the GM that things will work the way they should, and gives me deeper immersion due to greater versimilitude.
While this is simply opinion on my part, I feel Shadowrun (and RPGs in general) works much better in longer campaigns this way.