Critique on Kalama Sutta: Is Buddhism bad for Buddhism?
Since the Kalamas were confused in what they should or not believe, The Buddha instructed that they should be pragmatic and adopt only views and conduct which would lead to their well-being and peace of mind insted of keep bothering themselves with unverifiable competing doctrines which would lead to nowhere but to stressful mind states.

This is unrelated to the examples you give regarding the traditional customs of the monks and the Sangha because the customs are not harmful per se, they may be actually a source of joy, which serves to propel the practice. It all comes to how you relate to it, as long as there is Right View, there is no harm. 

The monks would be sabotaging themselves if they start raise against traditional customs just because their wrong personal view (disregarding the issue of dukkha) say so 
(which is conceit, ingratitude and cling to self-view). The practice delineated by the Buddha intend to end all stress building up the proper conditions, and to do so, is necessary to settle the attention to the proper frame of reference. Any other preoccupation is merely the mind being dragged by its passion over sensory phenomena. 


  This world is in bondage to attachments, clingings [sustenances], &amp;
  biases. But one such as this does not get involved with or cling to
  these attachments, clingings, fixations of awareness, biases,  or
  obsessions; nor is he resolved on ‘my self.’ He has no uncertainty or
  doubt that mere stress, when arising, is arising; stress, when passing
  away, is passing away. In this, his knowledge is  independent of
  others. It’s to this extent, Kaccāna, that there is right view.
  
  SN 12:15


For complementary explanantion of why clinging to personal views are nothing more than fuel to the fetters, See: AN 10:93 and MN 63 

Regarding the rebirth doctrine as it is decribed, it's  a attempt to explain a insight of  the Buddha himself. So it's suppose, for those who follows the Buddha's footsteps, to have such  experience (whatever it may be) as well at some point.
No one is demanding you to believe in it. However, aside of the feeling of samvega (disenchantment due the briefness nature of the sensory phenomena), having conviction in rebirth, will turn the 
practioner much more eager to go forth.