Some choice quotes:

". I realized that Creo is an extraordinary technological challenge and we achieved unbelievable results so far. Who could have developed a new multiplatform programming language with a blazing fast virtual machine? Who could have rewritten from scratch a mobile operating system fully UIKit compatible? Who could have a product like ours? Nobody, probably nobody in the world… and if YC’s choice was driven by the product than we would had no rivals."

Ok, you're amazing.

"I believe that our biggest mistake was to think that being able to develop such an extraordinary product could somehow give us an advantage against the thousand of other ideas presented at Y Combinator. We were wrong."

No, your biggest mistake was to think that you are somehow entitled to an investment and that YC was the lucky one. The opening sentence is indicative of that, according to you it started with a letter from YC to you, but in actual fact you applied first. So you're the seeker, you are the one initiating the relationship and you have to prove yourself worthy of the relationship.

"I really think that the complexity of the Creo project penalized us at YC."

Making something complex simple is a communications issue. If you can't step away from the complexity of the engine underneath your offering then you are not an effective person/entity to communicate with capital providers.

"the only thing that matters for them is the business model … I repeat here again: product has zero value."

You state this as though it is a fact, but it is just your opinion. In order I think that for YC team comes first, product/market fit second and business model last.

Then, the actual interview:

" In few words it’s an app that is able to create other apps. We have developed a new programming language with a multiplatform virtual machine and we have rewritten from scratch a mobile operating system (100% UIKit source compatible), all exposed through a desktop application that makes incredibly fast and easy the creation of mobile applications. Development time is reduced from weeks and months to few hours or days."

This is an old story in IT circles, it comes back every time there is a new medium, sooner or later someone will do 'cross-platform', that's not unique in and of itself.

"OK, but there are other similar technologies . For example …"

Did you let them finish their sentence?

" Creo: Xcode? (Have you read our apply?)"

If they had not you would not have been invited.

" … those are solutions that can be used only by professional developers, our software is for everyone, even for those who are not a developer."

That's another thing that's been said since COBOL about every new language/platform.

" YC: OK got it… so why should not I install Eclipse?"

" Creo: (Eclipse Holy God, you really just said Eclipse??)"

Yes, he did, but so what? If you're so incredibly smart that YC alumni seem stupid in comparison why can't you explain in a simple and easy to understand blurb what it is that your product does so that such confusion does not arise in the first place?

And so on...

" We came out of the interview dazed … neither I nor Daniele wanted to talk. My impression was that it was a complete disaster … two years of work, two years spent fighting for an idea that seemed impossible to become reality and in 10 minutes they had not even bothered to understand what we had in our hands. "

No, they did bother, you failed to explain. It's a communications problem on the sender side, the receivers would have been happy to understand you if you had taken the time and the trouble to explain it in their language rather than to expect them to accept the explanation in your language.

That's a pretty common mistake but it is unusual to see such a condenscending and frankly insulting attitude on the part of the person exhibiting the mistake. Your whole rant comes across as though you are somehow entitled to a certain treatment because of your technical expertise when in the real world what matters is how well you manage to communicate your achievements to your target audience (potential investors in this case) whoever they may be.

A few tips:

- turn down the rhetoric about how awesome you are until you have real world results, and preferably have others say how awesome you are

- go and work with your target audience instead of doing all your work behind closed doors

- focus on the product/market fit before you do more work

- get a dose of humility somewhere

- keep your dirty laundry in-house

Good luck!