If you think you shouldn't buy stock in a company because they have been "hacked"...heh, well, i guess you won't be buying any stock. Also...what percentage of companies that have been hacked do you think actually know about it? I'd guess less then 10% and i'd lean towards less then 1% that you hear about. You don't get to be considered a decent tight rope walker by falling.
As many people have said before in one way or another, its not a matter of whether something can be hacked, as how long it takes.
Number one concern shouldn't be security for a company intending to make money (well...outside of security companies anyway)...Number one should remain as how do i increase my worth or expand etc... If you are spending too much money or time* on security (or too little), you aren't going to make any money (or if too little, you'll end up paying for it...)... So as i said, it'll still be prioritized and test setups are (or maybe should) still going to be lower priority then more important systems or data. And again, doesn't excuse a door left open, but might explain some of it.