So I don't think the change will have much impact on Vintage players. Vintage is already so loaded with errata and rules changes that to be a competitive player, you basically have to memorize the oracle text for 100s of cards to begin with. The change to Lightning Bolt will be unnoticeable compare to the change to Time Vault or the various cards with completely changed functionality like Alpha Nether Shadow. In fact, my personal Lightning Bolts from Alpha will have more accurate rules text after the errata than they do now :) Compared to the massive rules changes between now and when I started, this is kind of minor.
I definitely think this is costly for new players, but I trust WotC on this one. I think this is an example of Wizards thinking very long term, and focusing on the design holistically, and reexamining very core beliefs, and treating the rules-set as a work in progress, and I think all of these things Wizards could do even more than they're doing now, so I applaud this effort.
Ignoring the logistics of errata, this makes planeswalkers a lot more intuitive ... I expect most new players already thought the rules worked this way (the old rules were genuinely kind of silly ... they added a lot of complexity and no depth)
- Flavour-wise, I liked that walkers were in a unique space between players and creatures - they felt like the powerful allies they seem designed to be. Now, they're basically 0 power creatures with defender and activated abilites. Meh.
Just a quick callout, attacking planeswalkers is unchanged. You're still deciding "Do I attack Andy? or do I attack Jace?". Since many cards which damage players will continue to damage planeswalkers in the future, I think Planeswalkers are still going to hold a very unique spot in the game as "mini players." There is a pretty gigantic difference between this and a creature with Defender (if you could chose whether or not to block with Jace ... good lord would that card be overpowered)
Things are very confusing now, but in a few years a huge portion of players will have never played the game with the old rules-set, and a large number of them may NEVER own a card that was printed before this change. Once we hit that point, the built-in downside of a rules change/errata being confusing vanishes. If you expect magic to be around for another 20 years, these sorts of changes are a necessity.