You know what, let's try it that way and see what happens.
The only way to "try it that way" is for a conservative to actually win the nomination. And I'm all in favor of that, but that hasn't happened for...a long time.
We've tried "liberal-lite" in each of the last three presidential cycles in the hopes of drawing in the cross-over votes. We'll see how it ends today, but it hasn't worked out very well so far. Insanity is doing the same thing over and over and expecting a different result. Let's try something different and see what happens.
The problem is that there is no collective hive-mind of voters to decide "let's do something different". It's all just masses of individuals gravitating towards the particular candidates they like. Think about those who voted for Kasich, or Bush. Do you really think this election will convince
them that they should support Ted Cruz the next time around? I think it'll be exactly the opposite -- they'll think that their more liberal brand of Republicanism is still the ticket to winning the general election. Or how about the Trump supporters embittered at #neverTrumpers. Are they all going to decide to vote for Cruz because you "taught them a lesson"?
People don't think/act that way.
I don't vote to send a message or out of spite.
I didn't say you did. I said that in the next election, a lot of people may vote based on spite. I hope I'm wrong, but I suspect this won't be a defeat that will draw us closer. It will be a defeat that will lead to nasty recriminations that will last for years.