The idea is to stop kids looking like chavs or getting bullied for not wearing Nike clothing. Personally I agree with uniform, as long as its practical and can be bought from Asda, or from the school for ASDA prices.
I had to Google Asda to know what you were talking about, and having done so, I agree with all the points you have made.
Public schools in Australia which have a uniform policy (not all of them do) maintain that it's good for school pride and that it promotes equality among all students. Ideally, uniform would be cheap, reasonably flattering to the appearance, easily-maintained, and available in seasonally-appropriate styles. It would be adopted only after extensive consultation with stakeholders (parents, Parents' and Citizens' Committees, etc.); and plenty of advance warning would be given on the school's expectations, enforcement, and changes. A used-clothing pool might make it easier for families on limited incomes to comply with requirements.
The school in the Kent Online article appears to have fallen down on most if not all of those points, going by the comments made.
ETA: Many of the comments, both from parents and students, contained atrocious spelling and grammar errors.