No, it would not be in the investors best interest to make that change. Under the current system all of the money spent is used to buy shares in the company. Under a system where the VC firm was responsible for their own legal fees then $25k (or whatever) would go directly to the lawyers instead of buying shares so they would end up with a bit less ownership.
EDIT: To be clear I'm not saying that I am in favor of the status quo. I am not. I'm just saying that it is understandable given the incentives of VC firms.