Running

Nope. Easy is easy. At the start of the plan you're just building up strength and getting used to time spent on your feet. If you go off too hard early on you'll be more likely to get injured.
You'll find most of the improvement comes from long slow runs, and they have to be easy enough that you can recover properly inbetween (so that you can do another long, slow run).
Your easy pace will get faster as you progress anyway, but that should be a product of your improving fitness rather than forcing it.

+1 .Guessing your doing the first timer plan, not the improvement one.
Endurance fitness takes a long time to come good. Muscles, tendons and bones take a while to adapt and strengthen, so time on feet is still valuable to build a strong and reliable chassis. Its relatively quicker to build up cardio vascular fitness and potentially have a fairly powerful engine that could break a weaker chassis.

If you've reached the end of week 4, uninjured and a little bit fitter then thats the important bit. As you start to work on speedier sessions, your easy paced runs (ones where you can still chat comfortably) will actually become quicker... unless you shackle yourself by purely running to mile split times and needlessly slow down.