i wouldn't say it a fashion or sth regarding this issue.
but cantonese especially those in hong kong are now less aware of the correctness of the pronounciation
- the replacement of " n- " with " l- ";
- the omission of " ng- ";
- the replacement of " ng- " with " m- ".
the fact is the MISTAKES seem to be acceptable WIDELY by most people. no one will eager to correct the speaker the pronounciation not even by some of the irresponsible teachers!!! the worst is when you speak it the correct way, you will be treated as an "ET" saying that you are just "overstrict". however, on the other hand, there are people read it affectedly. they do not omit the " ng-" but try to read it as if it is another character i.e., the sounding of the " ng- " is far too looooonnngg than it should be!!! the nasal part is too STRONG that trying to "overwhelm" the whole character.
my little advice is to keep on reading it correctly, but do not alter the "tempo" of each character (too much).
for example, say " ngOh " but do not say " NNGGOH "