Can simple puzzle tag can created . Many people don't like very big very difficult questions .
If I had to choose, I would vote no.
Such a tag would be a meta-tag - one that doesn't define what the puzzle is about, or the content of the puzzle, but instead is dependent on other tags. Also, this tag would mean different things to different people - TheGreatEscaper might find Question 16 Ripple Effect easy, while others who aren't so experienced at grid-deduction might find it fiendishly difficult.
A second (perhaps less important reason) is that it would encourage lower-quality puzzles - where perhaps not so much effort has been put into making them (hence them being "simple").
Lastly, using Gareth McCaughan's informal defintion of a good tag - being useful in searches. Since the tag means different things to different people, either we tag a lot of puzzles with simple when someone finds it simple, reducing its search usefulness; we only tag puzzles with simple when there is a consensus on its simpleness, which also reduces its usefulness because there will be puzzles many think are simple but some don't agree; or, there is no criterion on whether a puzzle is simple, which would mean that it doesn't mean anything in particular - so searching with simple is as likely to help as searching without.
So, as a result of these three things, I don't think we should create a simple tag.
See Jeff Atwood's blog post for more on meta-tags.