Commitment to FRAND is voluntary, not mandatory, and ETSI does not set the terms. Each company does.
I think you are misinterpreting that.
Nobody can
force a company to declare any of their IP "Standards Essential." Company XYZ could come up with a way of quadrupling the amount of data you could send over a 3G or 802.11 connection, and ETSI couldn't force them to to make that technology part of the next standard specification.
However, a company that did declare it Standard Essential would gain a tremendous commercial advantage. To begin with, they would have a pretty-much guaranteed royalty revenue stream, albeit at a "less-than-bank robbery" rate. But more importantly, thanks to "Network Effects" their newly developed technology becomes much more valuable because it is considered Standards Essential: Its not much good designing a chip that can send or receive data very quickly if there are only a few devices it can communicate with.
Its not mandatory to make FRAND commitments. But
once you do, you have to live up to the commitments you made. Samsung's failure to live up to its FRAND commitments is believed to be the reason they are being investigated by the EU; and why its extremely likely Motorola and Samsung will find themselves facing Anti-Trust action from the US Justice Department.
Also, the "Requirement for Royalty-Free Cross Licensing" refers
only to other FRAND-encumbered patents that are part of the same standard. Motorola can't force Cisco to cross-license its patents on IP-switching technology (which aren't part of the ETSI Standard-Essential pool).
This, by the way, is the heart of what Motorola (and by default Google) and Samsung are trying to do. For all their protestations to the contrary, they aren't really looking to get licensing money from Apple. What they really want is to try and force Apple to cross-license its non-Frand smartphone IP (ie. scroll and bounce back, multitouch, touch-to-e-mail, etc.) patents.