First and foremost, this needs to be addressed:
DO NOT CITE EVENTHUBS AS AN AUTHENTIC TIER LIST.
This isn't a criticism or jab at your dignity, it's actual advice. Eventhubs may be good for many things, but tier lists are not one of them. They are open to public voting and inevitably turn into mass popularity contests. Not a good rubric for character placement.
That said, I have to ask: why would you even need to consult a tier list to decide who to play? Smash 4 is still relatively young and it's nigh-on impossible to construct a communally accepted, truly accurate tier list with the data we currently have, especially considering that data is being changed and reassessed every couple of months. Add in customs and we have a whole 'nother element to consider that just complicates things even further.
There's also the fact that tiers make much less of a tangible difference in this game than in previous games. It isn't like Melee, where Fox and Marth dominate the charts, or Brawl with its abyssal difference in character viability: it's relatively balanced and every character is, at some level, competitively viable. Some more so than others, naturally, though if you're a good player, you can mitigate almost any matchup. No character is objectively awful and the impetus is therefore on you to attain the best results with the toolset at your disposal.
Now, to answer your question: why is Palutena so low on most people's individual tier lists, as well as many community-wide aggregate results? There are a few reasons:
- Slow, laggy smashes and tilts, in addition to a lack of quick-response moves, make it difficult for her to counter rushdown fighters that tend to dominate the upper tiers
- Methodical and paced playstyle is difficult to get used to and tends to alienate a lot of new players
- Default special set is designed for defensive play that, again, does not work well against faster and more aggressive fighters
- She's just not that popular and there are very few high-level players helping to advance her metagame
That said, she's definitely not a poor character. She has a great deal of potential under her ostensibly low-tier surface, particularly in customs, which is where she really shines. While I don't agree with the notion that you should let tiers define who you play as, if it really does matter to you, then I'd say there's still no reason to drop Palutena: if you like playing as her and you get good results with her, then that's what you should consider in the end.