With Canon introduced EOS 650d with touch screen, does it have an useful effect on photographers?
Will this storm drive other manufacturers too or will it fade away just with this?
Also is there any real benefit of touch screen in DSLR?
Touch screens are "here to stay".
There are things that can be done better with a touch screen than with any human interface "I/O" method presently available on cameras. They add abilities at relatively low cost and are interactive and the interface is dynamically adaptive to meet situation and user needs.
When shooting in the field, the touchscreen will be rarely used because it's slower to look at and then touch a screen rather than feeling a button and pressing it. Amateurs and casuals users are the target customer for touch screens in these devices. For previewing an image, many people will find it nice to swipe between photos and zoom in. But while-shooting, it's really all about the average joe - not so much the enthusiast/professional shooter.
I found the touch screen to be a good addition to Canon 650D:
iPhone-like pintch-to-zoom and image to image swiping with a finger.
Compared to a 600D, I was able to navigate between different settings in Quick Control Display (when pressing the 'Q' button) much quicker.
It is also possible to completely disable the touchscreen functionality should you so desire.