It's not about "Can we make money in the future" with EA. It's about "Can we make money right now?" And with Sims 4, they can. With Sims 5, in a couple of years time, there's a risk that this time, people won't want to go through the process of having to buy another 30 packs. That even if they get Sims 5 base, they won't want its DLC. As for Microtransactions, they're still going on, but their golden age is coming to an end as people finally realise how exploitative they are now. If Sims 5 can come out after the age of the Microtransaction, so much the better. But if it's STARTED during the age of the transaction, it'll flop when it does come out.
We've heard nothing about a Sims 5 that isn't just fans hyping rumors up, only to be disappointed, which is why I'm not convinced Sims 5 is even in the making besides rich people saying, "Should we make another FIFA, or start work on Sims 5?" EA have said that Sims 4 has another three years in it yet. That's a lot of packs. And Sims 5 won't come out as long as packs are being made for Sims 4.