Maybe for projects such as OpenSSL and other "infrastructural" software, but choosing a copyleft licence for e.g. a compiler/runtime library would be IMO a mistake. For example, LLVM chose a non-copyleft open-source licence, and one of the main issues preventing OCaml from becoming more mainstream is its horrible licence (which is actually much worse than GPL, as it requires that all modifications to code be distributed as original code + a patch).