It makes economic sense... if you plan to ever update the software (especially more than a small handful of times). For most software, that's a pretty sane assumption, but there's a fairly important niche where it's not: embedded firmware, all the way from the GUI of some random thing-with-a-cheap-LCD to device drivers for flagship Android phones (which are more likely to be in the "small handful" category than "never", but still). In the latter case, even though Linux is under the GPL, at the rate the hardware changes there is often little incentive to contribute back to mainline. Or fulfill GPL obligations at all, for that matter - but at least most big Western manufacturers have some place to get a source dump. If Linux were BSD-licensed, things would be even worse.