‘Pushover’ is another term for ‘permissive’. It emphasises the fact that, unlike copyleft licences, pushover licences don’t make an attempt to protect the freedoms they grant their users. In other words, they allow anyone to make and distribute derivative works without preserving any of the freedoms which came with the original work.
As far as I can see, for an author of derivative work, permissive licences are only really preferable when you either can’t or don’t want to grant or preserve the freedoms which a copyleft licence would require you to grant and preserve. (Which, to be fair, may often be the case.) From a different point of view, copyleft can be seen as better for embedding, since it means that Free Software in question will only be used to make more Free Software.
The MPL is a copyleft licence, but it’s known as a ‘weak copyleft’ licence. That means it preserves only the freedom of the program it initially covers; any changes made directly to that program can only be distributed as Free Software, but the program itself may be used and distributed as part of a larger work, which as a whole does not have to be Free. (This is in contrast to ‘strong copyleft’ licences like the GPL, which require the entire larger work to be Free.)
Weak copyleft is a kind of compromise which lets you e.g. embed a piece of software without having to grant all your users freedom to use, share and modify your entire work, but you're still required to grant them those freedoms in regard to the piece you’re embedding.
As far as I can see, for an author of derivative work, permissive licences are only really preferable when you either can’t or don’t want to grant or preserve the freedoms which a copyleft licence would require you to grant and preserve. (Which, to be fair, may often be the case.) From a different point of view, copyleft can be seen as better for embedding, since it means that Free Software in question will only be used to make more Free Software.
The MPL is a copyleft licence, but it’s known as a ‘weak copyleft’ licence. That means it preserves only the freedom of the program it initially covers; any changes made directly to that program can only be distributed as Free Software, but the program itself may be used and distributed as part of a larger work, which as a whole does not have to be Free. (This is in contrast to ‘strong copyleft’ licences like the GPL, which require the entire larger work to be Free.)
Weak copyleft is a kind of compromise which lets you e.g. embed a piece of software without having to grant all your users freedom to use, share and modify your entire work, but you're still required to grant them those freedoms in regard to the piece you’re embedding.