It is NOT a very smart business decision. The choice ISN'T stay onsite vs. stay offsite. The choice is go to WDW or go somewhere else.
The decision to go to WDW is hard. While the level of entertainment is exceptional, the cost to go to WDW is huge. At present, the decision to go to WDW is only marginally better than going somewhere cheaper. The decision is only palatable because of the quality and low-cost of offsite lodging.
I can rent an entire new 3000 sq ft offsite house, with a private pool, for less than a 260 sq ft cinderblock special at All-Star Music.
If I am forced to pay a ton of extra money to stay in those tiny little rooms that WDW offers just so I can avoid more lines, then I simply will not go to WDW any more.
Last week, I had to decide between going to a fancy, expensive steakhouse, or going to the chain restaurant Outback Steak house. If the decision were marginal, I would go with the cheaper one. If the fancy steakhouse were more important, I'd wait a couple weeks to save for it.
You say "The decision to go to Disney is hard" Than you say
"The decision to go to Disney is only marginally better than elsewhere"
It sounds contradictory to me.
You can't expect to get the same thing for less than those who paid to be onsite. Someone said that they don't need the perks (such as buses), so they stay offsite where it is cheaper. Maybe Disney is trying to make the onsite perks more appealing by adding FP+ pre-booking. Offsites still get it- the day of.
Many resorts offer perks that people don't use, but still pay for. Many resorts have fitness centers people don't use. or have mandatory resort surcharges that include amenities some won't use.
I think it is a good business decision.