I might not be a proponent of Mobile Web advertising such as banner ads (annoying push advertising that takes up precious screen space). But there is a HUGE advantage mobile web has over SMS Campaigns. Anonymity. Consumer's have not caught on yet, but they will when a brand breaks the covenant with consumers, but when you send a call action US Shortcode (Text Number) you are sending your phone number with it. There is no rules against a Brand or Agency using your number in the future to contact you. Technically by giving your number in an SMS campaign it is very possible the Do Not Call Registry does not apply since you gave the number blindly by signing up for future promotions.
Mobile Web si different. You are accessing the WWW via a IP point. So your direct phone number is not being transferred every time you access a mobile web site. And when Mobile Web Ad Blocking Software get's developed you will be able to download an APP to block banner Ads.
I truly feel that SMS is superior for Mobile Marketing for two specific areas: Immediate gratification with a coupon or free offer. Or using SMS as a launch pad to your Mobile Website Content. These are very measurable, tasteful, and unintrusive. These are call to actions that are permissive and thus truly powerful for Consumer Engagement.
There also should be plainly written expectations on a website to explain policies to consumers that if they send the SMS Shortcode a brand is not taking advantage and adding their phone number to a database unawares. If you ask people if they would give out their phone number to a brand most would say "Why, What for, or No!". If you ask them if they are aware they are giving out their phone number when sending an SMS Code the answer would most likely be they didn't realize this.