Is there any reason not to have tube phono stage ?

@atmasphere Nicely explained. Is that the only reason (RF) that increasing the load resistor value appears to brighten (open) up the top end of a MC?

Another reason not to use transistor phono stage, and LOMCs. Just use MM/MI like in old good times.

Is that the only reason (RF) that increasing the load resistor value appears to brighten (open) up the top end of a MC?

@noromance If the load resistance is too high, the resonant peak can still make energy. RFI really messes with audio electronics; the more gain the more it seems to affect it. We're talking about this RFI injected directly into the input of the phono section via the tonearm cable itself. 

If you were able to install an RF filter than went low enough you'd find the problem eliminated in that manner as well but its easier to design the phono section to be immune to that in the first place. 

 Not really, a good ss phono stage is designed not to overload in the way  @atmasphere has outlined, a cheap one Wii have issues.  A cheap tube stage will also sound bad.  However, cheap and inexpensive are not the same thing.  For under $1500 the Hagerman Trumpet MC or MM is a great product.  
 

 Not really, a good ss phono stage is designed not to overload in the way  @atmasphere has outlined

@oceanica 

A simple way to know if there is a problem is to see what 'cartridge loading' provisions the preamp has. If a switch on the front panel, its a good bet the preamp would otherwise be affected by the RFI previously described. 

If it does not have a problem with the RFI then there would be no need for the 'cartridge loading' provision unless the preamp was to be used with a high output MM cartridge.