Why is it said that a random energy distribution in the early universe is more natural than a uniform one? From Wikipedia:

The horizon problem is the problem of determining why the Universe appears statistically homogeneous and isotropic in accordance with the cosmological principle. For example, molecules in a canister of gas are distributed homogeneously and isotropically because they are in thermal equilibrium: gas throughout the canister has had enough time to interact to dissipate inhomogeneities and anisotropies. The situation is quite different in the big bang model without inflation, because gravitational expansion does not give the early universe enough time to equilibrate.

https://en.wikipedia.org/wiki/Inflation_(cosmology)
The argument is that the early universe could not have had time to evolve to thermal equilibrium without an inflationary period. But why we are assuming that the early universe needed to evolve into this state in the first place? Why couldn't it have formed already in thermal equilibrium? The quoted argument seems to make unnecessary assumptions. To suggest that the universe needed time to equilibrate is to suggest that it was once - sometime prior to recombination - not in a state of thermal equilibrium, correct? But why would we make such an assumption?
I have had a look at this Why does the homogeneity of the universe require inflation? question and the accepted answer claims:

Creating a universe where the temperatures were random in different parts of space and had an opportunity to come in thermal equilibrium before going out of causal contact (as a result of inflation) is more natural

But I don't agree that this is more 'natural'. To me this logic is totally backwards. A universe with a random temperature distribution is much harder to explain than a uniform one. If you're going to suggest that the early universe contained random energy fluctuations, surely you have to explain why that would be the case? If the entire universe somehow came into being in one great Big Bang, then surely it makes significantly more sense that it would be the same temperature and composition at every point in space? Only developing anisotropies afterwards (probably due to quantum fluctuations).
 A: 
The argument is that the early universe could not have had time to evolve to thermal equilibrium without an inflationary period.

This is a misunderstanding of the argument. When one looks at the most perfect black body radiation curve we have measured , the cosmic microwave background curve

it is evident that we see a thermal equilibrium, but the puzzle is not that time was needed, it was that the different regions in space could not communicate between themselves due to the light cone problem of special and general  relativity. There could be no interactions between  the masses in the total region observed of the CMB because no energy and momentum could be exchanged between them due to the velocity of light being c, and the light cone of each region:

Given an event E, the light cone classifies all events in spacetime into 5 distinct categories:
Events on the future light cone of E.
Events on the past light cone of E.
Events inside the future light cone of E are those affected by a material >particle emitted at E.
Events inside the past light cone of E are those that can emit a material particle and affect what is happening at E.
All other events are in the (absolute) elsewhere of E and are those that cannot affect or be affected by E.

It is the elsewhere part of the universe part of it seen in the CMB plot

that is the problem.
Now a model that would posit a "uniform big bang"  as a hypothesis, is less attractive than the inflation model, which assumes quantization of gravity and the inflaton field doing the homogenisation .

It explains the origin of the large-scale structure of the cosmos. Quantum fluctuations in the microscopic inflationary region, magnified to cosmic size, become the seeds for the growth of structure in the Universe (see galaxy formation and evolution and structure formation). Many physicists also believe that inflation explains why the Universe appears to be the same in all directions (isotropic), why the cosmic microwave background radiation is distributed evenly, why the Universe is flat, and why no magnetic monopoles have been observed.

So it is a hypothesis that satisfies most physicists, but is still open to research , particularly as quantization of gravity is still an effective theory and no definite model has been established.
