Why did shrI puraMdara dAsa introduce rAga mAyAmALavagowLa for the lessons and learning methodologies that he designed in karnATic classical music.

This post is my humble attempt in trying to find out as to why dAsashrEShTa shrI puraMdara dAsa chose the rAga mAyAmALavagowLa for the lessons and learning methodologies he designed in karnATic classical music.

[ While reading this, you might want to consider listening to these peaceful stotras: 

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1. There is an uncommonly popular, (which sounds obvious to an artist and musicologist; and experienced rasikAs/listeners/admirers) notion, that he chose this raaga because of the very well placed swara positions (sa-r₁-ga₃-ma₁-pa-dha₁-ni₃). Here, if the student can get at ga₃ correctly during aarOhaNa then ma₁ is just one swara higher and same concept applies for the avarOhaNa too. That is the next swarAs scoffold on the previous swarAs. Also, this is a sampUrNa rAga (it is mELakarta rAga in todays system of classification of rAgAs) that is, has all the seven swarAs in it.
2. The above point is no doubt true and accurate, but, there are other rAgAs where this nature of scaffolding of swarAs occur. So why did he not choose them and instead choose mAyAmALavagowLa only (there is kalyAni, there is pantuvarALi, there is shaMkarAbharaNa, there is chArukEshi, etc..).
1. mAyAmALavagowLa is a very auspicious and divine rAga capable of evoking the divinity and spirituality within the artist and as well as the listener. As mentioned in the page about karnATic classical music, spirituality and seeing divinity is the backbone and nerve center of karnATic classical music, and while learning this music system, one should be able to feel the divinity while trying to learn. Hence, a rAga which has this capability is chosen and one of such a rAga happens to be mAyAmALavagowLa. But still why did he choose this rAga? There are other rAgAs like nAdanAmakriye which seems soo tailor made only for devOtional aspects.
• When some of the swarAs goes missing or absent, the part of the devotional aspect (or the particular rAga bhAva) which would have been otherwise brought out by these swarA(s) (that is if they were present, as in the case of its parent rAga) is also now absent, and hence lacks the effectiveness of the parent raaga, mAyAmALavagowLa, in bringing out the full scale of that particular devotional bhAva that was intended by Shri. Purandara dAsa. 
• Hence, on one hand choosing a asampUrNa krama rAga does not serve the purpose well (like rEvagupti/bowLi) and neither does choosing a sampUrNa akrama rAga like nAdanAmakriye serve the purpose well, because in the case of sampUrNa akrama rAga, it is difficult to learn in the very intial/beginning stages. 
• Taking the mAyAmALavagowLa and lets say, we introduce sarwaswrakampita gamaka. In this case, mAyAmALavagowLa becomes akin to the hindustAni rAga "bhairav" which also is a morning rAga. Though this rAga is devotionally very rich, it is too deep and very mature and too heavy. This primarily poses three problems
• Many of the beginners are kids (even of just 2 to 4 yrs of age, kids come with no experience in life whatsoever. Such a deep strong emotion will be difficult for them to handle and might even have an impact on their coming understanding of the world. This rAga is klishTa in order to be practiced at the beginning stages. (i am not talking of prodigies like Chitraveena Ravikiran, they are have completely different and advanced karnATic mindset, gifTed by GOD)).
• In mAyAmALavagowLa, the madhyama takes hardly any gamaka, hence, it acts as a kind of possible resting place for a learner, especially in the vocal stream. Also, there is an excellent opportunity to learn the art of learning to know intuitively, which swara recieves a gamaka and which does not, in a particular rAga which is actually very important factor because, there are numerous rAgAs, haveing the same swaras but different gamakaprayOgas, in the karnATic classical music itself.
• It needs time to develop strength, voice culture and stamina (and even finger dexterity if learning on an instrument) to do sarvaswara gamaka prayOgas, in order to effectively bring out the heavy rAga such as bhairav, which young kids and most later stage learners lack to some extent, either small or large. 
2. mAyAmALavagowLa is a morning rAga, that is a rAga effective when sung or played in morning. This rAga is a parent for the rAga malahari (meaning destroyer of all malina (or mala or impurities/adulterations) - basically in the mind and heart). Hence, in a way, the purifying nature of the rAga malahari is inherently present in this rAga (but this nature of purifying quality gets amplified in malahari to a greater extent than in mAyAmALavagowLa, but it is present). Hence, it cleanses the mind, of impurities and evil thoughts when sung (or even practiced in the beginning stages). Also, this rAga is the parent of rAgas called boWLi and rEvagupti, two very near rAgas, both know for their divine aspects. Hence, all these rAgA bhAvas are to a great extent inherent in mAyAmALavagowLa. 

 For all the above reasons (many more might be there!!), I believe Shri. Purandara dAsa chose the wonderful rAga mAyAmALavagowLa for composing beginner lessons for students in karnATaka shAstrIya saMgIta

-Sunil Anandatheertha