Trivial is perhaps the wrong word for them. A more accurate term might be "inevitable" (in the short-term). The reason why patents exist is to protect inventions which are difficult to come up with and which may not exist without patent protection. Pharmaceuticals are a good example, it takes a lot of research to design a new potential drug and even more painstaking research to prove that it works and is safe, if you can't guarantee some sort of market protection that gives the developer a chance to recoup their R&D costs then it's questionable whether or not you'd have as many new drugs.
But on the other hand, if a patented invention is something that several other folks in the industry would have invented within the next 5 years regardless then patents start to become a drag on progress. It's telling when you see a burst of progress happen after a patent runs out, and that sort of thing happens all the time. The question is how do we strike the right balance. Unfortunately right now there are some very strong forces intent on keeping things very much off balance.
The pharmaceutical industry also provides us with plenty of opportunities to pick on them. Take a drug that's about to go off-patent, make a trivial change to their process, get a fast-track approval from FDA (because it's essentially the same), and a new patent (because it's new and improved!). Competitors play this game too, making copycat drugs which are very similar enough for marketing, but just different enough to deserve their own patent. I'm having a hard time sympathizing with any pharmaceutical company. Disclaimer, I'm almost done reading Goldacre's new book.
If A is patented, A+B is covered by A's patent AND B's patent.
The only way to avoid A is to use a non-patented yet critical invention. The inventor of A should have included any such thing as one of their patent claims.
But on the other hand, if a patented invention is something that several other folks in the industry would have invented within the next 5 years regardless then patents start to become a drag on progress. It's telling when you see a burst of progress happen after a patent runs out, and that sort of thing happens all the time. The question is how do we strike the right balance. Unfortunately right now there are some very strong forces intent on keeping things very much off balance.