Yes it was. They announced that they would no longer require it for warranty maintenance shorty after I purchased it.
EDIT: Yes, it was the Service visits that were compulsory, not the Plan. I bought the pre-paid plan because it was cheaper than a-la-carte since i was going to "have" to do it anyway.
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I would think "necessary" hardware upgrades would be a warranty issue irrespective of the Plan.
Here's archived version
Tesla Service | Tesla Motors