Writing from Australia, you are not aware of the legislation in place in England and Wales which means that intinction for the laity is not an option in England and Wales.
(1) In 1976 the Bishops' Conference determined that the choice of whether to receive in the hand or on the tongue was the communicant's choice alone, and not the minister's.
Therefore if a priest or minister offers Communion by intinction, they are in breach of the liturgical law established by the Bishops' decision since they effectively remove the communicant's choice, as already stated in this thread.
(2) A person also may not self-intinct because this comes into the category of self-service Communion banned by paragraph 9 of the instruction Inaestimabile Donum in 1980, as already stated in this thread (and as also laid down in the paragraph you quoted from Celebrating the Mass).
In England and Wales it is well known that the result of this combination of liturgical laws is that intinction for lay people may never licitly take place in these countries, whatever Redemptionis Sacramentum may say. An Australian would not know this.
Regarding the paragraph you quote from the Bishops' 2005 document Celebrating the Mass, the drafters of that document did not wish to appear to be openly contradicting the possibility of receiving by intinction which may be an option in other countries, and were fully aware that the wording "not recommended" in practice would have the same force as "not permitted" in the light of our local legislation as cited above. The instructions given for doing intinction are in fact redundant, once again in the light of our local legislation. You will have noted that in the case of a priest or minister illicitly offering Communion only by intinction, the communicant is reminded that he or she has the option not to receive by intinction, which is in complete conformity with the 1976 legislation.