It's up to you if you want to sign into the hotel iPad using your iTunes account, so you can ask that iPad to play music over your own iOS devices. Thus there seems to be no reason to do so, unless of course you forgot your own iOS devices for some reason.
I thought the discussion was over hotel chains having Siri-enabled devices waiting in the rooms. Perhaps I misread the article?
As for "gathering data", one would presume that they would "collect" the same kind of info that any good hotel would... such as remembering your breakfast and movie preferences, for the next time you stay at one of their chain places.
I'm pretty sure you've participated in other threads where I've brought this up and explained exactly what data is gathered. It goes about twenty levels deeper than you think.
Oh for goodness' sake. How would they get "voice prints" from either an iPad or Echo?
I'm hoping you're joking. If not, then where do I start explaining this?
The entire concept of something like Cortana, Alexa, and "OK Google" comes down to two things: learn everything about anything the client does, and develop an ever more accurate digital print of the client's voice. To be frank the whole purpose is to copy the client in software, and be able to anticipate their desires. Voice prints can give a great deal of information about the mental state of the client using stress analysis, but also, they can be used for nefarious purposes. As if having such prints in the first place isn't nefarious enough, using speech synthesis software, a voice print with modal variables, and VOIP technology, a "call from that guy" could be faked. A person's entire life could be stolen, wrecked, or they could just be manipulated for some purpose. It could be government, it could be private.
Analog voice print technology has been around since the 50's. Digital came along in the 1980s but the processing power wasn't there to make it commercially viable until the 1990s. It initially drove secure office network assistants like Wildfire back in the mid to late 1990s, and that is where all of today's current digital voice assistants originated.
Even our own Steve Jobs demonstrated this concept on stage at WWDC. Remember "My voice is my password"? That is voice print technology.