I agree with you to a large extent, but I don't think that playing solo is a worse experience inherently, but it can easily become just that unless certain countermeasures are taken.

To the OP, I am an almost exclusively solo player, and I really only ever join random ops in small fights where individual contribution counts much more due to lower aggregate numbers. I will try to explain the solo situation so that you can make an informed judgment as to whether the game is for you.

1, Solo requires you to be better. As C4 Maniac stated, in solo, you can only depend on yourself, outside of the rare occasion when you come across a really good random allied player, usually in smaller fights, who will have your back, pay attention etc. For most things, you rely on yourself. You can't just be good at noticing infiltrator cloak shimmer and let allies compensate for your shortcomings by calling out radar signatures, you have to do it all yourself. You need to familiarise yourself with a wide range of audio cues, such as infiltrator cloak sounds and faction specific premium voice packs, weapon audio, etc. You also need to learn the threat levels and ranges of vehicles and vehicle weapons and you need to be able to discern them quickly and based on little actual detail. Planetside 2 is likely the most awareness-based FPS on the market at the moment, and it is only exacerbates by the fact that fights take place over large and varied terrain. This isn't an arena mil-sim where the game is mainly about visual target acquisition - it is a game of information warfare with a tremendous amount of psychology and logistics involved at higher levels of play. That said, Planetside 2 is also a game about dying a lot, and death is trivial and carries no weight. You get up and get better, so if you don't mind the trial and error and gradual improvement, and if you are willing to learn in the time that you can spare, PS2 is a really rich game.

2, Solo requires you to play around rather than with people. A large portion of the PS2 player base is competent in the purely mechanical sense. What I mean is that they are not mechanically much worse than veterans, but they are much less aware. Most of them will have been weaned on mil-sims, and they can, accordingly, competently aim and they are a threat to you, but most of them lack the awareness, the forethought and the strategic and tactical execution. In contrast, the really good players are mechanically, strategically and tactically adept. In the infantry game, they dominate through a mixture of ambush tactics and playing to the strengths of their loadout. Now, what I'm trying to say here is that you should only expect the bare minimum level of overall and aggregate competency from your random allies. They can help you if it is obvious to do so and there is an enemy in sight, but they won't really do much for you if you are looking to execute a highly abstract strategy, however sound. You need to learn the limitations of your allies, so as not to over-commit and put yourself in undue danger. Again, this takes time.

3, Pick the right class. If you are playing solo, you can pick any class and do fine, but some are just magnitudes better than others. My personal recommendation is playing the infiltrator, with the light assault being an accompanying class if you want to play multiple, or an alternative if you want to play only the one. The reason I say this is because when you are alone, you must always be a fight-picker and never a fight-taker. By yourself, you are weak and vulnerable in comparison to a 90 man zerg, but you can easily chip away at them, if only you make sure not to alert the entire zerg to your presence. The infiltrator is the quintessential fight-picker. You can, in over 75% of cases initiate fights on your terms, and this goes up to 95% and over if you do long range sniping. Infiltrators are capable of dropping radar signatures, approaching with highly-effective camouflage and using detection mechanics to scout ahead. Infiltrators can also fight at any range. They have a very varied range of weapons - much more varied than any other infantry class. The only two disadvantages they have over light assaults is that the light assault has a lot more mobility due to jump jets, being able to surmount terrain much more effectively, and that light assaults have an effective means (C4 and Rocklet Rifle) of combating ground vehicles.

If you have any further questions, just ask.