Besides, for a big one-time expense for a computer, those extra 100$ should barely be noticed in comparison to the rest of the rig.
Needed: Sure not. An i5 works fine. Recommended: Anytime, unless you'll have to live on instant-ramen for weeks because of it.
All that for a measly extra $100.
Just saying ^^
I have a i5 and my brother has the i7...so happy I didn't spend the extra cash just so I can say I did.
i7-4770k - GTX 780 Ti - 16GB DDR3 Ripjaws - (2) HyperX 120s / Vertex 3 120
ASRock Extreme3 - Sennheiser Momentums - Xonar DG - EVGA Supernova 650G - Corsair H80i
The i7 is superior for many tasks, that's true. However, the i5 is equal to an i7 in 95% of all tasks out there. If you are a professional user and do a bit of rendering etc. then of course, you aren't looking for an i5. If you are a normal user that games and run a few light programs in addition to games, you aren't looking for an i7. If budget is of no concern I cannot see a reason not to get an i7 cause it will give you 1-2 fps extra etc. and it will give you a better performance should you want to render or compress/encode etc. If on a budget, there is no way you can justify an i7 over say, a better gpu/HDD/SSD/whatever.