I agree that something based strongly on principle rather than convenience is less likely to drift from them, for better and for worse.
Free software doesn't need to be copyleft, though. The MIT license, for example, is a free software license, even though it's not copyleft. Projects such as the various flavours of BSD can have pretty strong principles regarding their software distributions remaining free even though they don't prefer copyleft.
> flavours of BSD can have pretty strong principles regarding their software distributions remaining free even though they don't prefer copyleft
That is true, however speaking to many members of the FreeBSD community in particular, there seems to be a strong sentiment of this simply being a practical model of development, rather than a strong ideological stance. In fact a large portion seems to be rocking Macs, "cause it's BSD anyway", which to me does not seem particularly principled.
In fact they seem to take pride in completely closed systems being based on FreeBSD, like the PS4, Nintendo Switch etc.
Free software doesn't need to be copyleft, though. The MIT license, for example, is a free software license, even though it's not copyleft. Projects such as the various flavours of BSD can have pretty strong principles regarding their software distributions remaining free even though they don't prefer copyleft.