It's not just the product cycles are much shorter, for software the time to independent (re)discovery is so short patent protection serves no purpose.
That's partly because the ideas being patented right now are so ludicrously primitive they would inevitably be 'discovered' by average programmers as soon as they needed to solve that problem. Patent protection is about scarcity of innovation, encouraging sharing for the good of all. But the patents being issued aren't for innovation with any sort of scarcity to it.
More important: software is the 1st example of the 'infinite monkeys typing' concept. We have so many people writing software, sufficient of them being creative doing it that invention is a tidal flood, not a scarce trickle.
What's wrong with software patents is the failure to properly account for both those aspects, that without scarcity there's no need to protect trivial discoveries. Instead the patent offices have stampeded the other way and allowed everything, however trivial or obvious to get protection.