The graphics in older PDX look the way they do due to hardware limitations not because they were trying to make low quality graphics to give some sort of authentic feel.
Beyond my claim that PDX's newer games were 'shinier' as slightly negative-toned critique, I only referred to V2 as an example of a previous good artistic choice. I didn't mean to indicate that their old games were superior aesthetically, and PDX's games have obviously experienced a natural evolution in the visual department throughout their history. It's a pretty significant difference in terms of the amount of details between for example Victoria 2 (2010) vs EU3 (2007).
While I could agree with the description of EU3 map as 'low quality' for various reasons. I don't agree with that view when it concerns Victoria 2 however, especially when the arguments basically amounts to this stereotype: "It's a fugly game because it's not in 3D like CK2 and EU4!!!".
Hardware limitations, though? In terms of hardware requirements it has always been the processor that has been the bottleneck in terms of performance for PDS games. Classically, their engines has rigorously used the processor's power (and memory in few cases), with the GPU being more idle in terms of significance. You can easily see this as their older games pre-V2 are playable to a larger degree with an integrated/poor GPU. With Paradox change from 2D-map to a more stylistic 3D-map, as a result their games became more GPU-intensive, though not significantly compared to other genres. For example the issue in general with poor CK2 performance isn't for the vast majority due to neither the 3D map nor poor GPUs, but rather in the limitations of processing power and memory.
While hardware was probably an important factor for Paradox decisions regarding the graphical outlook of their games, and perhaps not regarded as a priority for their targeted market. Of course in terms of hardware requirements not many had powerful enough rigs to handle medium to extremely graphic-intensive games at least early in Paradox game development history, but you could hardly classify Paradox's later 3D-map games Sengoku, CK2 and EU4 in the graphic-intensive category.
This seems to suggest that it wasn't hardware, but the engine itself that couldn't handle more intensive graphical work. Sengoku was released just a year after Victoria 2, and with that game their engine Clausewitz had evolved, and the map design had been shifted towards 3D style. Which both was possible due to the rework on their engine and most importantly a change in their design philosophy in favor of 3D-maps easily apparent in their later games.
My apologizes for going somewhat off-topic with a large post.