This might become the Catholic Controversy of the week. The Deacon Bench has A priest writes: “Why I refuse to bless children at communion”
I largely see the points and issues the Priest is saying here. Further I have another major concern that we are feeding a mindset at a very young age that one must every week get into the communion line. Though perhaps one is not properly diposed to receive communion. In fact perhaps the blessing of Children in large numbers feeds that mentality to the adults in the pews.
There is another related issue. The blessing of adults which is often largely non Cathoic adults. Often at Parish ,especially during Weddings and Funerals , we see this done. I actually like this practice in many ways. Sort of dampers down the WHY CAN'T TAKE COMMUNION people from being upset , and makes them feel connected in some ways to the liturgy in a more personal way. I find this very very common. Of course the same valid objections to this not being part of the liturgy rite as explained above in the article remains.
In the end as to both but especially the Children issue I suspect Priests that have concerns will put this down the list of battles they have to fight to get the Liturgy back to it's proper place. You can't fight a huge number of these Liturgical battles all at once. Though I get the concern.
Also lets face it. This has been going on for so long that now it feels a normal part of the rite too. For I know the Pope himself might do it on occasion too. Personally asillicit innovations to take care of during the Liturgy this might be well down my list if I was a Bishop or Priest. But of course I am not.