For sure Khyber Pakhtuns and Punjabi voters are being more selective toward development goals and that's why whoever takes over both provinces tends to be under pressure or they know they will get the boot come the elections.
Karachiites are actually selective towards development too, I don't support the MQM but they did get lots support cause of the work Mustafa Kamal(he left mqm later) did during his 3 years ruling khi, if you visited karachi before 2005 and then again in 2008 you would notice a stark difference in infrastructure and it had gotten cleaner, everything got worse once PPP came and removed the LB system, people did get fed up with MQM+PPP that's why PTI is the 2nd most popular party here & my area NA250 voted for PTI, they also polled 2nd in every constuincy, so people are waking up
Karachi and Sindh. This province unfortunatly is trapped around the ethnic divide. Almost 70 years after the Mohajirs migrated from India they have still not integrated into Sindh, instead they just have carved a block - I can't say that this has not happened in other parts of the world although I think this example is rather unique.
That's no out of choice, it's simply becauseit's cause Sindhis are in small numbers here & only started growing, it's still less than 1/10th Sindhi, was even less 30-40 years back, you only assimilate eventually when you interact with the host ethnicity, that's how gradually you learn the language & culture and intermarry etc, many people may not know this but lots of muhajirs had settled in interior Sindh and can speak Sindhi fluently and some married Sindhis, samething in Punjab there were many urdu-speaking migrants from India picked up punjabi & don't identify as mohajir, so it's not like mohajirs in karachi don't want to assiilate or won't, it's not happening cause of the demographics and lack of interaction with sidhis, this is not like lahore or peshawar where you can find the natives easily; people here can curse in pashto & undertand seraiki now cause we have so many pashtuns and seraikis but still can't speak sindhi despite learning it in school, even Gujaratis in khi who are a large %age of the city are adopting urdu and merging into the Urdu-speaking community despite being culturally,linguistically like Sindhis, the baloch in karachi are also getting urduized and being absorbed into the urdu-speaking community and it's cause they're majority whereas Sindhis are few.
Sindhis are increasing in number but not enough to impact the culture, if anything they're acting like Urdu-speakers now, just check any Sindhi from Khi on tv like Zarrar Khuhro,Fahad Mustafa or Sanam Baloch, their accent and mannerism have little trace of Sindhiness
Of course like I have said before my knowledge of this part of Pakistan is extremely limited and I wait for others 'on the ground' to correct me.
*The MQM bile for PTI/Pashtuns/Imran Khan is I believe driven by the population change that Karachi has seen in the last 30 years and will see in next 20 years which threatens their monopoly.
Most PTI supporters in Khi are in fact Urdu-speakers, so mqm is losing ground not cause of pashtuns but thier own target demographic