you are discussing 2 different things one its subjective and the other is technical, its obvious PS2 is better because there are more impresive games in PS2 compared to DC, try comparing shemue to hitman blood money or soul calibur with its sequels or gran turismo vs DC racers, also DC games used discreet polygons characters in lot of games, try comparing mortal kombat 4 vs MK Armageddon, DC have impresive games like le mans but their effect are less common in other games compared to PS2 games
when it comes to technical its not "obsiously" or subjective things, there are specs and how they can be used, they impact the perception of the game
PS2 had problems with its resolution yes but it can use its edram as it needed so there is not a restriction to resolution there are games with 640x480 resolution and even use super sampling in top of that(grand prix challenge) and the linux kit uses 1024x768 as resolution so it depends the developer and how they use the edram, other consoles like GC have a fixed space for resolution 2MB for framebuffer+zbuffer DC has way more memory as a resutl most PS2 and GC games settled for under 640x4080 resolution, are you going to claim that DC is better than GC? it indeed have more space and generally better resolution but does that make DC overall better than PS2 or GC? no
DC good textures capabilities comes mainly from its really good compression algorithm and in part its size in comparison PS2 uses CLUT as compression and whatever amount of space you want to use in edram(tipically 2 MB) but on PS2 the configuration is different, on edram you put a texture cache that is way faster than DC so the correct way of using it is to stream textures from main ram(wich is bigger in PS2 vs DC) devs at first had trouble using it and wanted to use edram like vram on PC or DC, on DC you have a bigger space for textures on vram but vram is way slower so you cant make as much updates to it per frame as on PS2, GC uses a similar aproach to PS2, it has 1 MB texture cache with very fast access and a good compression algorithm(around 2 times better than ps2) so DC have more space than both consoles but it cant match their textures cache speed, if devs cant use the texture cache system properly then a DC port will look better overall
there are games with good texture resolution like phantasy star online floor and walls but thare are also games with lot of low resolution textures like shenmue that shows how some games can concentrate big textures in fewer objects and had to use lower textures when lot of different textures are required also sonic 2 seems to have better textures on DC compared to GC, is dreamcast better machine? no it just has it pros and drawbacks
DC software matured really fast thanks to how easy to use was the system and was way more mature by the time other systems released, it released first, but it has the drawback that there is a lot fixed function on DC, in comparison PS2 was very hard to use because it introduced lot of freedom and not a stablished path for making games, the devkit recommend 3 different rendering paths each with it pros and cons and the simpler and recomended doesnt use most of the system, DC use its CPU for tranformation and light so it can be programmed for many effect that indeed require more maturity but PS2 have programmable VU that require a lot of work but are also way faster than what the DC can do, that is way there are per pixel effects in complex scenes where in DC they cost a lot and can be used in more limited like the famous normal mapped coin in shenmue in contrast we see normal mapping in games like hitman blood money and matrix path of neo everywhere and that on top of other effects like depth of field and complex light that most DC games lack doesnt mean DC cant do a complex game with complex effects but its not simple and is more limited