This is only the first instance that came to mind. If I must find more I will, suffice to say you can ring onto a Goa'uld ship pretty easily.

The reason its not used regularly is because of boarding action 101. If you aren't going in with a far superior force, you're wasteing forces.

And this is one of the worst mistakes a GM can make. Never assume you've thought of everything, because you haven't. I have stopped counting the number of times my players have surprised me totally when I thought I'd accounted for everything. Believe me, there are most definitely ways to make things go wrong that you have not thought of.
I also have not thought of all of them, but as an example I will give some things that could go wrong on Ariadne's theoretical assault on the Ha'tak.
Debris strikes the 302, crippling it and ensuring they cannot escape with it or forcing them to land in a bay cut off from their destination on the Ha'tak.
She arrives in the engine room, only to find that there are no spare crystals and her ability is limited to yanking the crystals already there.
Alternatively, perhaps she arrives and in the firefight a staff blast hits some important crystals, maybe even damaging the crystal receptacle, at which point she has to work to bypass it, if it can be salvaged at all.

I just came up with those things in the past few minutes, and all are things I would willingly write in as happening to my own char, GM or no. Never underestimate players.