Well if your teeth are tipped in at some point your going to need to tip them out. It would be a problem perhaps if it were to happen too fast. My view is that is largely what orthodontics would be achieving on an adult except where they are doing palate expansion. My experience of mewing etc has been that what happened at first was expansion of the palate and now what I need to do and am mostly doing is tipping the teeth out to the correct angle. I have not encountered any negative  sensations or effects. If it were something that was happening before expansion I might question whether this was happening as a result of lateral pressure on the teeth rather than on the palate. I have a feeling that expansion then tipping is the right order but I have no clear idea why.

As Odys suggests, teeth tipping can be desirable if your teeth start out lingually inclined and need to be uprighted. In the context of palate expansion, teeth tipping is often mentioned to distinguish between skeletal and dental changes. It is thought that chewing exercises can help keep your teeth upright during expansion to avoid flaring out in the buccal direction.

Not when your teeth are lingually tipped. This allows more mandibular upswing 

@Apollo What kind of chewing exercises do you recommend? Just mastic gum/towel chewing for about an hour a day? 

Also @EddieMoney how does teeth tipping allow for more mandibular upswing? I'm curious. And do you think that for people (like me) who've had orthodontic work done for teeth straightening still possibly benefit from teeth tipping in regards to more mandibular upswing? And if so, would it be worth sacrificing teeth straightness for more mandibular upswing?