It makes no difference to the reader. Or if it does, they will probably prefer the less formal. It makes a difference to some companies, but most are discovering that a more informal style makes them seem less stuffy and more approachable.
The idea that a "formal" style was more appropriate for technical communication has two roots. One is in the entirely appropriate desire that technical communication should be precise. The other is in the use of language as a form of class distinction, in which certain forms are used to distinguish the speech of the educated from that of the uneducated.
The latter is largely moribund among the general population, but still popular with a class of editor and grammar fiends, for more or less the old reasons: as a mark of distinction, to set themselves apart from the hoipoloi.
The concern with precision is as relevant as ever, but there is an increasing recognition that a formal precision that is not actually expressed in the language of the reader does nothing to lead the common reader to correct action. In any case, contractions do nothing to reduce precision.