This has been most interesting debate...
...and the solution to this problem is Lamrim, as usual.
In the original Lamrim-scheme of Atisha, there are four scopes of motivation to religious practice:
- the wish to have happiness in this life
- the wish to have happiness in the next life
- the wish to have permanent cessation of all suffering (liberation)
- the wish that everyone would have permanent cessation of all suffering (full enlightenment)
Later, the tradition collated the first two scopes into one. But nevertheless, it is quite clear, that there is nothing wrong or un-dharmic in approaching the Three Jewels from the perspective of finding a better life just here and now. There are loads of Suttas where Buddha Shakyamuni explains all kinds of methods for "this-worldly happiness and prosperity" - how to treat one's spouse for a happy marriage, how to invest the business profits for a pleasurable and secure future, how to avoid angering all kinds of local spirits for a calamity free life, and so forth. All this is Dharma, as found in Pali Canon, and as classified as the very start of the path to enlightenment in the Lamrim.
There are those who start meditating because they want mental peace and more harmonious relationships, there are those who start practicing because they want success to their family business. The first reason might be more prevalent in the 'modern West', and the latter in the 'traditional East', but still, they are both on the same level of being the very start of the religious path.
If one approaches a Dharmapala so that one could achieve mental fortitude, luck in business, or freedom from interfering spirits, it is all right indeed, for it is just that very Dharma, the first stage of Lamrim, the start of the Path.
If Pabongkhapa said somewhere at some point to some listeners that "practice for this life is not Dharma", he either did not know the Suttas or the Lamrim, or else he was trying to shake a little some lazy hedonists in his audience. I would bet the latter option rings more true.
Now of course, if one defines true Dharma practice as being free from the eight worldly concerns, as is sometimes done, then Pabongkhapa was totally right indeed, but by that token, almost nobody would practice any Dharma, so that definition cannot be taken as a generally valid one but as a specific statement intended for specific audiences. This must be true, because there are other definitions of true Dharma as well that relate to other stages of Lamrim. True Dharma can also be said to start from the stage of Mahayana bodhichitta, or Hinayana renunciation, or general Refuge arising from fear of lower rebirth and faith in the Three Jewels, this latter being implied by the freedom from eight worldly concerns.
And furthermore, for example, there are many many prayers given by Buddha himself and by great lineage-masters, where Tara is especially invoked to help in "this-worldly matters", like saving from the eight fears, or granting offspring, or bestowing success to one's business, or averting spirits. In short, there is nothing un-dharmic in praying and practicing for the happiness of this life. It is in fact the very start of Lamrim. If it is in harmony with Pali Suttas, Lamrim-teachings, and Tara practices, it must be okay with Dorje Shugden as well.
blessings,
Zhalmed Pawo