The service is no good if it only has tracks from artists in the top 40. That's what the problem was with the initial streaming offerings years ago. Yeah, it has a few artists on it - but not necessarily all of the ones you want.
For a streaming service to be successful it needs to have pretty much everything a customer wants on it in order for them to pay for it.
The big artists aren't the ones that are going to hurt from the 3 months without pay. It's the smaller ones who have bills to pay that are. It's been widely reported for quite a while that artists receive peanuts from streaming royalties. So instead of one of the richest companies in the world with billions in the bank eating this 'relatively' small cost to promote their new untested service in order to gain market share, they decide to stiff the artists that they want to hop on board and evangelise the service?
You think Apple aren't going to make that money back in order of magnitudes from subscription fees if the free trial works taking their substantial cut?
Artists can't make music forever out of love itself. They need to get paid too, they have bills to pay. Taylor Swift's fans have proved themselves devoted enough to buy her albums outright online without streaming. I can't remember the exact details, but I'm pretty sure her last album was only released to buy, not stream, and it sold in record numbers. She is the exception, most artists don't have that loyal a following.
Apple needs the artists on boards as much as they need Apple.
I don't know, it's just feels off to me that Apple have approached it in this way. If they want to pull a 3 months free publicity stunt to steal away subscribers from other streaming services, they shouldn't do it to the detriment of the income of the artists they're trying to 'help'.