Yes, technology patents are useful.
Regarding the Amazon patent you referred to, it only covers Amazon's one-click ordering (and similar single-action ordering), and it is immensely valuable to Amazon. Their competitors (essentially, anyone who sells things online) would love to use a similar system, but to do so, they must either pay Amazon a licensing fee or risk being sued for patent infringement.
Beyond the value that patents can bring in court or at the negotiation table, and the value that they can have in dissuading potential competitors from taking away your business, patents can also have great defensive value. Some technology companies amass vast collections of patents for defensive purposes. They do not necessarily plan to sue anyone for patent infringement, but if one of their competitors were to sue them, they have the arsenal to effectively countersue.