Hi @Pondera
Thanks for these questions/criticisms here. From what you say it appears you haven’t practiced in this way? But maybe you should give it a go?! 
It’s useful to have a litte experience about any subject before making judgements 
“Concentration” does make it sound like a lot of hard work, or a forceful, pressured, intense effort, doesn’t it? For this reason many experienced meditation teachers avoid using the word “concentration” for samadhi, because it sends the wrong message, and they use words like “stillness” or “steadiness” instead. Makes a big difference doesn’t it? So perhaps there’s a problem of translation rather than technique?
“Concentration” as a tense, forced effort is the exact opposite of the tranquility that comes from samatha meditation like anapanasati or the breath nimitta. So jhana nimitta teachers like Ajahn Brahm (who uses the term"stillness") and others talk about relaxing the body, calming the mind, letting go, becoming peaceful, developing a natural mindfulness, which deepens all by it self and becomes very pleasurable due to the arising of piti and sukkha, becoming more stable and stable in stillness, along with the nimitta. And the same sequence of events described in the sutta you quote above all occur and keep occuring as samadhi deepens. Remember, too that there is a difference between ordinary samadhi, and samma sammadhi, (right samadhi, right stillness, right absorption, right immersion, right concentration even… ) which is jhana.
Again this is a translation issue, not a technique issue and does not reflect a particular approach at all . There are many words used for “piti”; such as, zest, enthusiasm, joy, rapture and thrill to mention a few translations. It doesn’t indicate much except the preference of the translator. The experience of piti can be very broad, from a minor tingling to deep throbbing suffusion. So maybe it’s difficult to pin down the breadth of this experience in just one term that covers it all. Often ‘joy’ is also used to translate as ‘pamujja/pamojja’ , but some translators do use ‘joy’ for piti, which is their choice… Some translate sukha as happiness. Others translate it as pleasure, some as bliss. So translation is not an exact science and we shouldn’t get too caught up on a single term but rather have a more flexible approach based on an experienced teachers instructions, along with our own experience and also be comfortable with more synonyms. You could even try doing some translation yourself too!
Yes. Piti sukha is experienced with a nimitta. Ajahn Brahm calls the nimitta path bliss upon bliss upon bliss.
Teachers would say, it is not that the “self is lost” in the nimitta but more that the usual mind/body boundaries of self are starting to dissolve.
Hope that helps answers your question/criticisms. 
PS
If you want to know more about nimitta and piti, check out Piya Tan’s useful essay here:
> http://www.themindingcentre.org/dharmafarer/wp-content/uploads/2009/12/19.7-Nimitta-piya.pdf
Ohhhh and I’ve just discovered this thread here! Thanks @Gabriel. Excellent!