It is horses for courses. I probably wouldn't buy a car online (I do use the web for research along with selection of potential sellers), unless I was really happy with the security of the seller, and so it goes down from there really.
Banks stating with the introduction of IF and Egg have really started going down this route, and Natwest decided to go for those who want a branch and more contact, they never off shored their customer telephone support, for example.
Hot Tubs, well I am probably going to go down to a showroom, unless the online deal is significantly less, and then say it was a good price at 500 quid, I would checkout the length of time the business had been trading online, and if anyone had problems.
Before buying I would research the hottub, and there I would prefer responses via email from an initial web form, rather than phone. To close the deal I might phone, but I would judge more on the emails and if there was problem there then I might phone, if I still have questions or want to see exactly what I am buying then off to the showroom. So, yes having the full suite of contact for hottub selling makes sense.
But, if I am buying computer parts, I want the site to work for me, and not have to get on the phone, and computer parts can be more than a hottub, but I know that area better, so a combination of cost and how familiar one is with the item perhaps.