No because the main transaction is your payment for the flight
Everything else is incidental or supports it.
The comparison you may be thinking of is 'person walks into a bar, looks at drinks menu, buys none, hangs out for an hour and then leaves. Bartender sees them leaving and thinks 'how rude'.
However that is NOT the situation with an airline seat. ...
Put it this way. You ask for a catalog, you just don't disclose that you already have no intention to buy, because you don't have to, then start reading it.
After you finish, you return it to the attendants.
You simply didn't find anything interesting/worth to buy
No one is obligated to buy anything. How often... have you entered a shop, looked and walked ...
Put it this way. Suppose they kept copies of Nature Magazine for passengers to read on request. Would it be impolite to ask for a copy? You have no intention of buying anything, since in our fantasy world, Nature is entirely editorial and has no advertisements.
Of course not. The magazine is there for you to browse to pass the time.
The same applies ...