Seems to uneedly clutter the forum. If you want to buy something from ocuk having taht there isn't going to sell it too you. Most people post spec topics etc constantly browsing the shop and updating their basket. I fail to see how its much of a selling point?
It might not appeal to you but others (including myself) will find it handy. It might not induce me to buy something specific in the way that a direct advert would but it will certainly make it easier to browse to the correct location once I've done my research.
I have bookmarks for other online stores and it would be as easy for me to click on one of those and navigate to the product I want as it would to click on the OcUK logo and navigate their shop. If there is a handy link to the correct section of the shop, I am more likely to click on that since it saves me the hassle of navigating through the shop.
At the end of the day, it won't put people off buying from the shop, it doesn't cost anything to implement, it doesn't really inconvenience anybody and it may get the shop a few more sales - so why not do it? As for it "uneedly" cluttering the forum - tosh and piffle. The main page is a gateway to the rest of the forums, most people only look at it for a few seconds at a time. Are you, and all the other detractors really trying to suggest that it lessens your enjoyment of the forums?