Most people will justify the size of the cities by saying that the game takes place in skyrim a cold wasteland where mostly nords live.Morrowind was a province where mostly dark elves live but still balmora for example is bigger than whiterun.
The other 4 cities of skyrim are somewhat good.Solitude at first looks big but after spending 5 walking around u have seen it all.The market area is nice but the residential one looks haunted.
I liked Windhelm for its atmosphere.big walls and plenty of streets.this one looks like a proper city.
And last but not least Markarth and Riften were pretty good compared to the rest.Riften was big enough and behaves like a city.The market is crowded people walk around the streets and at night the taverns are full.
As for markarth i liked the city because of its unique dwemer architecture.It still could have been better though.
All of these cities dont compare in size with most oblivion cities.I remember the first time i walked in Leyawin Skingrad and cheydinhal i got lost and had to use the map.And these cities are not described as huge in lore.I didnt expect Bethesda to make cities like Imperial City in skyrim.that would go against lore.But cities are too small and it makes skyrim look like a deserted place.And the irony is that people complained in Oblivion that Cyrodiil lacks settlements and now Skyrim has a lot of big enough settlements (riverwood rorikstead etc) but cities are small.Bethesda needs to find a middle ground.Also people need to stop using imperial city as a size scale for all elder scrolls cities.Technology is advancing.If they could make solitude the size of imperial city i would be cool with it as long as it had depth and a satisfying population.I would use the bigger city of the game to judge the size of the other cities lorewise.
Whats your opinion on the cities of skyrim and generally the whole world scale?

It takes like thirty seconds to cross from one end of Vivec to the other on foot. Less if you have a decent levitation spell.