Aerating – Aerating will increase the soils air supply, and by doing so, aid the plants respiratory actions. Carefully timed in the spring just as the grasses are starting to think about growing roots, aerating can be very beneficial if the soil is compacted or low in benefits microorganisms.
Having said that, over-aerating, or aerating to often, can and will have a detrimental effect on the soil. Really aerating should be at most an occasional thing to relieve compaction, or as a means to inoculate the soil with beneficial microorganisms. Annual or semi-annual aerating is not only unnecessary, but will damage the soil in the long run.
What I recommend is to aerate in the early spring, if the soil really need it. While the holes are open, top-dress with a good quality compost, or a compost soil mix, compost tea, or effective microorganisms. Special note the compost tea and effective microorganisms do not really like ultra violet rays. So, if going that route, best do it on a cloudy day or late in the day to avoid killing everything your are adding to the soil before they can take cover under the surface.
Power Raking – Power raking on the other hand, is not necessary and WILL damage your soil in a very short time. The problem with power raking is that it is non-discriminate. I mean the power rake tears up both dead and living roots. Power raking begets more power raking. Don’t do it. If really necessary, a hand thatch rake can be used.
To much thatch in a lawn can be an issue as far as water and air getting to the soil and things like that. But, if there is too much thatch in the lawn, what that is saying is that there is not enough microbial activity breaking down, eating, and decomposing the grasses and other plants (there should be more than just grasses in the lawn) in the lawn. I recommend aerating in this scenario. While the holes are open I would top-dress with a really good quality compost, and take every effort to ensure it gets into the holes. If you really wanted to go the extra step I would time it so that you are in the final stages of cleaning up, as a light rain happens.
If you are using a municipal water supply remember that chlorine will kill all the microorganisms in the compost, so I would use a sprinkler that aerates the water as much as possible and gives the water as much time in the air to allow the chlorine to escape. And, I would also irrigate on the light side for a day or so to also the new bugs a chance to build some numbers.
Collect rainwater people! If for no other reason but to irrigate your property.