That's not really the point of BizSpark. It's to get you to the point where SW licenses aren't a huge expenditure. At my company we have a general policy on SW "If it will make you more productive -- buy it." No questions asked.
We spend over $200k/year on each developer. Almost no developer purchases $10k/year in SW, but if they did, it's really not that big of a cost for us. And if there's a small improvement in productivity it's worth it.
But for companies where everyone eats ramen, but only when on sale, the cost of licenses is a big deal. I've seen startups where they require each dev to buy their own machines. I've seen other startups that pay half their annual salary for the first year and then will double your salary the next year -- as a way to get out the gate with lower costs.
If MS SW has no value then it has no value if its free. But if it does have value then the license costs really aren't that substantial.