> So in a sense it is better to have one noncopyleft(free-to-all) license, than a copyleft+noncopyleft(free-to-all) dual license.
I don't see any point to a copyleft/noncopyleft dual license except in some odd case of perceived or actual license incompatibility.
> Also noncopyleft(free-to-all) means every user needs to get the software license separately,
I don't understand this point. A (typical) feature of both copyleft and noncopyleft FLOSS licenses is that you get the license without any particular ceremonial overhead (this is also true of many proprietary licenses).
> Another use-case (which is actually what I had in mind originally) is to have the noncopyleft license available to commercial entities but only for the final official binaries, at the same time have the source available under copyleft, with the hope that they return back the improvements to be incorporated in the future binaries for them.
Ah, if I understand you correctly that is a whole nother issue, and one I've been thinking about recently. Some weak copyleft licenses explicitly allow non-FLOSS licensing of binaries by licensees, but the source code can only be distributed under the copyleft license.