Your assertion:

... it is so easy to vote without even really reading the post

implies these other assertions:

• Because it's easy, lots of people do this (or there is a "common perception" that lots of people do this), and
• Having lots of votes cast this way damages the content and overall value of the site (so it should be harder to vote without reading a node).

I think both of these assertions are wrong. I don't have any proof, but I'm comfortable with the assumption that most monks vote sincerely and conscientiously, and I think actual voting trends generally support this assumption.

As for the impact of the current voting system on overall node content and quality, I don't see any evidence for the negative impact that you are asserting (and you haven't pointed to any such evidence).

What I've seen is: good nodes get more upvotes than mediocre and bad ones (really good nodes get a lot more), and nodes that are wrong, insulting, etc, get downvoted much more often than nodes that don't have these problems, "other things equal" (whatever that might mean in this context). Speaking for myself, seeing lots of positive XP on one of my nodes is a nice experience that encourages me to keep posting, and seeing negative votes tends to have a remedial effect. I don't see a problem that needs fixing here.

Readers should be able simply to express agreement or gratitude (or opposing sentiments) toward a given node, and their expression should be made visible to the node author, in a manner that is easy and anonymous, and does not clutter the site. That is what happens with the existing system.

As for actually requiring that one must post a reply to a node in order to vote on that node, this would seem to make voting redundant and pointless: presumably, the required reply would express the opinion that the vote would have done, but in a more cumbersome, time-consuming, wasteful manner.

This encourages respondents to demonstrate in their reply that they have understood the post to the extent that they are able to add, resolve, criticise constructively (rather than just by pressing the minus button) and so on.

So, maybe you're just saying: in order to downvote a node, you must post reply. If this is really what you meant, it certainly is a practice that many have wished and asked for -- though usually not by imposing a "policy" (and never by restricting upvotes as well as downvotes). I've seen a lot of people say "if you downvote me, please say why", and this is reasonable, but I don't think it should be required.

For example, we should all be able to downvote an egregiously trollish node without all of us having to reply to it. That would go against the old and time-proven advice: "Don't feed the trolls."