I just think a lot of devotees mistakenly assume it is 100% guarantee or at any rate relatively easy to arrive at one. They then cook up these ideas that they can do without meditation and precepts because such activities have no bearing on their future rebirth in the Pure Land. You don't have to bother with difficult practices because whether you do them or not, you've got a purported guarantee of being reborn in the Pure Land.
I know not everyone says this, but generally this is the attitude I often encounter with Pure Land advocates.
I don't think attaining Shinjin means that you can now sit on your ass, watch 5 hours of TV a day instead of meditating or studying dharma, and violate the precepts all you want. Japanese Pure Land was originally aimed at people who could not just up and leave their families for the monastery; who could not escape violating certain precepts as a consequence of their poverty. Fisherman, for example, had to kill every day in order to survive. Japan being an island, vegetarianism simply wasn't practical for everyone. These were poor, despirited people who felt they had no real hope for the future --in this life or the next; so why should they even bother to try at all? The value of what Honen and Shinran did was in giving these people hope and something to live for.
But just because they now had the certainty of Ojo and eventually enlightenment did not mean that these Buddhists could just become complacent and do whatever they wanted. I think Shinran, especially, made this very clear in how he dealt with his son Zenran.
Shinran and Honen gave people hope, but they also changed lives. There is a very famous story of a prostitute who witnessed Honen teaching one day and as a result gave up prostituting herself. I think the reasoning behind this was the following:
"Hey, I'm not damned to hell after all. Before it didn't matter what I did, I was still damned. Now it doesn't matter what I do, I'm grasped never to be forgotten."
The new attitude is a lot more positive and inspiring than the former one and I think this is what caused people to change their lives for the better even if, technically, doing so did not affect their chances of attaining Ojo.
Modern Jodo and Jodoshinshu Buddhists are a lot better off than their medieval counterparts. To violate precepts unnecessarily and live an empty, materialistic lifestyle is to be an ingrate towards Amida's gift. Much like how the nembutsu transformed from a means to attaining Ojo, to a grateful response to having attained it; so do our efforts to uphold the precepts, study dharma, and even meditate transform from a means to a response. I don't do these things because I expect to become enlightened. I do them because to do less would be to denigrate the primal vow and hurt sentient beings, including myself; worst of all, I might slander the dharma and drive others away from hearing and answering Amida's call.
Of course, as you have observed, not all Shin Buddhists share my attitude but I thought I would put it out there so it could be established that Honen and Shinran's doctrine in no way encourages laziness or precept breaking.