That's not necessarily true:
Definite periodical entertainment venues (like radio shows) don't necessarily have to subscribe to the "consumers are always right" mantra, and its implications (i.e. "always please the consumer"), because there is no positive action (outside of listening) needed from the listeners to bring in revenue. That's why "shock jocks" can "get away with" being so outlandish: people will tune in (thereby increasing their listener ratings, which they can in-turn use as leverage for larger ad-revenue streams) just to hear what they will say next. That is why NBC Radio quickly did an about-face on firing Howard Stern when their demo studies and ratings came back, and why countless other radio stations and corporations throughout the country have done similar things.
Anyway, back to the topic at hand: the Soriano and Z signing/extension were "who gives a shit about salary and contract-length, we're going for the World Series in the next 1-3 years" moves. The org hoped to cash in on what the team had in 06-07 for a WS or two, then after that nobody would give a shit if the team blew with a 38-year old Soriano and/or bat-shit crazy Big Z with immovable deals, everyone would still be riding high from the first WS win for the team in nearly a century (at that time).
All that being said, it was clear (even at the time of the signing) that the Cubs were over-betting their hand with Soriano, as they allowed one not-all-that-good season in the NL East to outweigh the "meh" rest of his career. As with Z, they overplayed their hand yet again (he had one really good season before they inked him to the extension, with the rest being of the "that's pretty good, but not worth top-MLB-starter money" type), but at least with him there was a hope that he would progress with age and hopefully stave off going insane.
It was a gamble that
could have worked out, but was ultimately not a very intelligent one, even without the aid of hindsight.