I opened a case with Garmin support about this, and they directed me to add my request via http://www.garmin.com/ideas
All we can do is flood them with requests. I know from my work in Customer Support that the "sqeaky wheel gets the grease".
Please give these people more feedback.
Need I say more, it´s been years since folks first brought this up as a much needed feature for Garmin Connect. I am still using another website in addition to Garmin Connect JUST to track my shoes´ mileage. Come on, it shouldn´t be that complicated to add this type of feature. You already have the best customer service out there. It would be great if you could also make sure that you are the ones providing the best software for using your own products. Thanks.