Absolutely nothing wrong with 70-80 degree temp on a CPU. I've seen 105 on a Core 2 in a Macbook (that is now 7 years old and still working).
Also, buying a laptop with a core i7 is probably the first mistake...
I have a low-end i5 in mine that runs very cool indeed (not Haswell, but generation before), and handles everything I throw at it (30 programs open, 100 browser tabs, etc.) with ease. Even a modern Core i3 is way more than most people need in a laptop.