Dear Carlita, In my understanding it is neither ‘wrong’ nor unskillful to want a good rebirth 
One of the beautiful and liberating things of the Law of Dependent Arising, is that it means that the conditions and time needs to be right, all the factors need to come together, in order for other things to occur. When this - then this…
The gradual training is a process of gradual step-by-step conditioning in a particular direction. One has to go through this process the whole way through the Noble 8 fold Path. There is a simile that from milk (+ specific conditions) comes curds, from curds comes butter, from butter comes ghee…
This illustrates a conditioned step by step transformation.
In the case of the Path, one has to put this cause and effect action, this conditioning process, into effect on ones own Mind. As such, one starts by a bit of Right View, which gives impetus to beginning to develop the factors of Sila. Here we see positive or wholesome desire in effect. This wholesome desire is to reduce suffering. This includes not wanting to be reborn in a plane of suffering, and to want a good re-birth. Of course this is not only a good, but a necessary thing Without this there would really be no motivation > effort > energy etc to provide the required momentum for practice.
It is truly wonderful and a win -win situation. As one moves along the Path everything keeps getting better. If the work isn’t finished before one dies, then one has moved to a better point, a good rebirth, and can start from a more advanced position to continue the process in the next life 
No way to loose on this Path!
Further, as one moves along the Path, and the conditioned transformation moves further along the process, and Right View keeps developing (can’t do it any faster!), as RV develops, this influences perception. As perception changes in line with RV and Wisdom, one grows dispassionate and naturally starts to develop Nibida towards many wordly things and renunciation/Nekkhama is a natural result.
As one moves further and further along this conditioned process, even the idea of existence is relinquished. This can really only occur once that the 3 characteristics are fully penetrated. If one still has any sense of self, then the desire for an end to existence is akin to annihilation. So there is no point in trying to push for this prematurely
The focus needs to be on developing the path and reconditioning oneself, to get to the point of seeing clearly, when Nibbana is a natural consequence. Dependent Arising - just beautiful
When this - then this
Wordling/puthujjana (+ conditions) > trainee > in the stream > Arahant > Nibbana
Here is a beautiful visual representation from Ven Yodha’s doodles about crossing to the other shore It’s in the beautiful Dhamma doodles thread
So it is my understanding that during the process of moving along the Path, ones Desires and the type of craving becomes more refined and skillful - less and less driven by defilements. So as in the Buddhas simile, the carpenter uses a finer peg to dislodge a larger/coarser peg, so too does one develop the skill to use ever more wholesome desires to move one further along the Path. It is necessary. SO please use the desire for a good rebirth to good effect :-D.
As craving is penetrated and understood it is increasingly (more deeply) relinquished. As the craving changes, so too does the desire for types of rebirths, (this is a natural process, not done by Will) becoming ever more refined - until finally - Extinguishment - Nibbana 
Just bringing it back to the question of the necessity for generosity. In my understanding, this is an absolute requirement in the first steps of the path and building the foundation for the gradual training. Without it the process won’t work. The path is structured to condition those who walk it… No sila > no samadhi > no Panna.
It is only with the abolishment of all craving - aranhantship - that it is no longer necessary. At this point the Buddha says that one no longer needs to carry the raft, but can put it down. What needed to be done has been done
Of course, being generous is always a wise way to behave for all the reasons outlined in the originally cited sutta… and there is no reason why it should cease with attainments, but at the conclusion of the path it is no longer necessary and there is no more craving (wholesome or unwholesome) driving it.
Enjoy the process and use it skillfully 
