Question: Fresh positive karma created in this life through good practice of mindfulness of Amituofo can help to dilute the effects of past negative karma as it generate much merits. However, if one attains a longer life (longevity) in this life as a result, does this not lead to clinging to Samsara, which is the opposite of aspiring for birth in Pure Land? Doesn’t this defeat the purpose of practice?
Answer: Having positive karma does not always equate to having longevity, though this is generally the case. In terms of Pure Land practice, truly positive karma can lead to swift birth in Pure Land, especially if one aspires to reach there quickly. This is departure from the suffering of Samsara and the attainment of true immeasurable longevity there, with all the time needed to attain Buddhahood.
Having longevity in this life does not always equate to attachment to Samsara. In terms of Pure Land practice, it can offer more time for us to practise better, for ensuring birth in Pure Land. Having more time is also useful for those who aspire to share the Pure Land teachings with more, out of compassion. (Instead of hastening, Pure Land practitioners generally depart for Pure Land when facing death naturally.)
[Questions by the named, with answers by other commenters]
Q: I think the more important question is to ask, “What is the purpose/goal of good practice of mindfulness of Amituofo?” Is it for rebirth in the Pureland or for good merits and blessings.
A: It can be for both.
Q: If it is for blessings, there are other methods.
A: If for both, there is the Pure Land method above.
Q: Does time (in this case staying longer) does matter?
A: Yes, as the longer the stay in Samsara as an unaccomplished being means the more suffering there is personally, while there is less efficiency in helping to free others from suffering.