I also like the more in-depth strategic advice by the previewer. It's refreshing to see actual interesting strategy advice since we usually just talk about weird edge cases that only Stef has to worry about while implementing and otherwise never matters.
Let me briefly explain why I don't.
Cards can only be new once. Part of the fun with Preview threads is that we have no clue how good or bad the revealed cards are. Go back to the Cornucopia previews from the main blog, it's really funny to read people's first reactions. It doesn't matter how good you are, it's very hard to hit the power level correctly until you play with it for real.
Except, by "we" I mean the people who haven't gotten to playtest Empires. When a playtester is giving strategy advice on a card, they're probably saying something correct because they got to play with the cards already. That ruins the fun. There's no surprise. I thought one of the revealed cards was going to be pretty good, then I read a Reddit comment from a playtester that said "no this card is pretty bad", and now I'm sad because I didn't get to discover that for myself.
If you want accurate strategic advice, it's best to wait until the set gets released. Preview threads are for wild speculation, rules questions, etc.
(If you're going to say I don't have to read it, I actually didn't read it, but now I'm have to avoid the top half of the first page because it's an information hazard.)