Is there a way of reaching out to Wolfram and suggest a feature for the next version of mathematica? I'm a bit disappointed that v11 still doesn't have it and I'd be open to discuss a bit about the details, that's why I'm afraid that contacting support with a simple request could be not very helpful. Or it may be, what's your experience?
Yes. Wolfram Technical Support is where you should send suggestions for Mathematica.
When you make a suggestion, it's important to make sure you are clear that you are making a suggestion and not requesting technical help. I would suggest even beginning the email with "I have a suggestion for Mathematica..." Sometimes people are unclear about what they want and it leads to confusion.
And sorry, the rest of this is a bit of a rant....
I'm a bit biased of course, since I've worked for Wolfram Technical Support, but I don't know of any other company that makes available an entire department of Phds in a wide range of disciplines like Wolfram Research does. Wolfram support is the most ridiculously qualified group of people to ever be so ingloriously labeled as "just tech support". If they are not qualified to handle your suggestion, they will at least know the right person in the company to talk to.
I understand that it can be very frustrating when your suggestions aren't given a high priority or quickly accepted. That is why there are many people who demand to be given direct email access to developers and project managers. And why there are people who demand to be engaged in long conversations about their ideas. That's just not feasible to do for everyone. Please keep your suggestions succinct and understand that they will forward your suggestion to the appropriate people who may or may not like them based on their merit, economic feasibility, and (because they are human) personal whims.
My only other suggestion is that you might discuss your idea on the mathematica stack exchange chat. There are plenty of people who will help you flesh out your suggestion and talk about why or why it might not be a good idea. Many of them work in the company or commonly make suggestions of their own.
I often send send suggestions for what I think would be improvements to Wolfram tech support. I try hard to make these suggestions clear, complete and well-focused. This is important, because I am sure receiving vague and rambling suggestions must very frustrating for tech support personnel and a waste of their time.
I have always received replies to my suggestions, thanking me for making them. Some of them have even eventually shown up in Mathematica. I recently received three emails from tech support, each telling me that a suggestion I had made had been implemented in V11. One these suggestions was made over three years ago. I had forgotten all about it. So don't expect instant gratification :-) In fact, don't expect gratification at all.
It was likely in all three cases, my suggestion was one of many along similar lines. And that's why it's important that you bring your suggestions to the attention of WRI. The more people who make similar, reasonable suggestions, the more likely those suggestions will get implemented.