I see many similarities in films to the point where I can often guess what will happen next,even if the part was intended to be suspenseful. is that bad writing? should "plot twists" always be surprising or do viewers/readers expect a level of predictability?
There's an easy answer: It depends on the genre. Generally speaking, genre readers (that is, detective fiction, science fiction, fantasy, romance) will expect a certain degree of predictability - you are in control of the degree, knowing that some pleasant twists and surprises are welcome, but something too experimental will probably be received less warmly.
The exact opposite is the case with literary fiction, which is based first and foremost on in-depth characters, complex emotions and situations, and impossible dilemmas. Things can be predictable there (because people can be predictable), but your approach and resolution should, generally speaking, not be. After all, good literary fiction depends mostly on characters rather than plot.
EDIT: I now see your tag "screenwriting". It's basically the same with films. If you're writing a thriller, an adventure film, a detective story, then you've got to follow certain stereotypes and be a bit predictable at least in your structure. Also, do keep in mind that all this is also conceived in terms of marketing (or, to put it less prosaically, in terms of audience reaction). If you're writing simply for your own pleasure (which ideally should be the goal for all artistic endeavors), there are no limits
Surprise is the cheapest of literary devices. People often reread their favorite books and re-watch their favorite movies. They would not do so if their enjoyment of them depended on surprise. With effective storytelling our hearts can still be in our mouths for a character at a critical juncture no matter how often we have read the story. If we can enjoy a story even when we know exactly what is going to happen, then predictability of plot is not a problem in itself.
When people complain about predictability in fiction, I think what they are referring to is predictability in the writing itself, the writer's use of cheap and easy tricks and emotional manipulations, of stock ill-developed characters, or heroes and villains without subtlety. They are complaining that it is like every other book in the telling.
One of my writing professors is a fellow believer of the notion that everything is cliche. Almost everything has been done before, and redone many times over.
The question is, can you write it in a way that your characters are still unique and interesting? Lots of things can be similar, but still different, and entertaining. In comics many characters are based off one another, but are still their own characters.
Take Hawkeye, and Green Arrow for example. They both use a bow, and are both super heroes, but they aren't exactly the same. The same can be said for plots.
TL;DR There is a reason they are called tropes.
Use of a predictable sequence can bore your audience but can also make them feel smart. There was an article that concluded that audiences preferred knowing the story (http://www.ew.com/article/2015/07/27/trailer-spoilers-southpaw). A predictable plot element is a miniature version of this. The audience knows what is going to happen ("Don't open the closet!"), still gets the thrill ("eek, it was just the cat!") and then awaits the expected conclusion ("yay, killer got her as she was walking away!"). Subverting this will challenge your audience, possibly not fulfilling their expectations.
This allows you to manipulate the audience by setting up what appears to be a predictable sequence that gets turned on its head (the film "Feast" does this repeatedly) but if not done well it can turn folks off. Obviously this is highly dependent on the genre and expected audience. A general audience film designed to appeal to the most people possible will typically eschew trope thwarting plot twists (or make the twist part of their marketing to craft expectations) while a more niche product must rely on changing up the plot in order to feel fresh and innovative.