Sorry to here your having so much trouble locating the "Feedback" options you seek, as far as I can read from you post, it's Excel that you are most interested in providing feedback for.
This feature request is very easy to achieve in several ways, via the program itself and various other online product specific blogs, live podcasts, seminars and via Microsoft's own Facebook page. To name a few and even directly via phone/email.
To provide just one option for you. I myself went to attempted to see how hard it's to provide feedback as you say it is buried and not clear. (I disagree, as I personally found it very easy/clear.)
Here are the steps I took (in under forty seconds) and completed this task.
First I opened my browser and went to the main Office website. (Please use the hyperlink I've high lightened for you for your conveyance, or you may prefer to type the address into your search bar, It's really a users preference how they locate a page/site as there is no right or wrong way, Bing it, main search address bar or hyperlink to get there, as long as you get there safely, quickly.) First of you will notice when you land on the page that right at the bottom of the page there is a "Feedback" option located there, I assumed you feel that this is not direct enough for you or not enough specific for your product choice. To gain greater in-depth options I then selected the "Support" option which is clearly marked at the top of the page next to Products. Then using the pull down tab simply select your product of choice, in this case Excel and just type Feedback. When the page opens second down from the list you will see "Provide Feedback" please open. This is product specific, where you can send your "pat on the backs" or anything else relating to this product.
As an extra feature for you There is also a specific community section relating to anything Excel in Excel Community which I've included for you, as an extra guide.
This is just a few easy and direct options for you to use to provide valued "Feedback" relating to Excel, there are others ways of course as listed above and others. As I have already said in my previous posts for any specific product feedback, then always begin with the product in questions main landing page. As this is the official direct informational sections for that product, not just sales and promotions as you have misunderstood. Also product specific news, reference, help, training and feedback.
As regards to your reference to outdated posts/boards, this will always be an issue with an ever evolving global live brand like Microsoft and the vastness of products, the guy's and girls are working hard in the background to find ways to get greater support and relevant information that the user is seeking cleaner, even faster as I type, things do take time. On way around this is for you to select the title options first at the start page of this community that are all relevant to your request and then use the search bar to enter your request. Or use the Windows.com main page, using the displayed search bar within this page will display results that you can select from the left hand side which are relevant to you.
Hope this helps
Have a great day!
Thanks!