In my opinion he is half right, that more money definitely does need to be spent on the side. But at the same time, we have spent an almighty amount of money on the side over the last 3/4/5 years too. I know that wasn't just Jose but regardless, so much money has been thrown around and there has been some really poor scouting and purchasing in truth.
LvG really did hurt us with some of the transfers made during his tenure, between wasting millions on players who aren't here anymore such as Di Maria / Memphis / Morgan, and other players that are good squad options but really aren't good enough to be starting players for the team such as Darmian / Blind / Rojo etc. Fellaini and Mata, after coming in during Moyes tenure, have had good moments & patches and (again) proved good squad options, but they aren't good enough to be starting every week either. This has led to having a very good squad, with players who can do a job for a couple of games, but really the main 11-15 players aren't good enough and more top quality is required.
Some players have just not cut it either (looking at you Mikhi), and while that can happen to any team purchasing a player, it seems to happen with regularity to us and we need to be having more care when scouting players, looking for the thing within a players personality that is going to push them to succeed every single game and want to give their all for us. United are a massive club, it's understandable that some good players elsewhere may not be able to make that extra step up to play for a huge club. Lingard isn't the best player in the squad, but I would have another 5 or 6 players with his attitude and drive, and I think he puts some of the other players to shame. Against Burnley he threw everything into getting something out of the game, while others looked like they couldn't honestly care any less.
Jose is right, there is some heavy investment required in certain areas. Pogba and Matic are brilliant on the whole in the midfield, but a third midfielder of real excellence is required too as when either Pogba or Matic are not there it is so obvious how short we are in midfield. Maybe Ander can become what he was last season but there has been no evidence of that in the first half of this season. I love Valencia and he is a great option for us but we really need a proper right back, and while Shaw has played well the last few games when given the chance, the jury is still out for a left back too. He might turn things round as well and it would be great to see, but in all probability we're going to need 2 full backs in the summer. Jose mentioned City signing full backs for big money, but look at the impact they have had. We need a wide player for the right hand side definitely, and we also need another forward to provide a different option. Lukaku is a good player despite having a rough time the now, and Martial and Rashford have the potential, but they are not the finished article, we need another option up top to lessen the load. In spite of all that, I honestly don't think we are a million miles away, I think it is just heavy spending for a key number of areas that would make all the difference to a very good squad.
The starting 11 definitely needs improved, no doubt about it. But I despair when I think of the money wasted in the last 3/4 years. We seem to have smartened up a bit under Jose and with purchases like Pogba / Matic / Lukaku we are intent on improving the starting 11, this must continue because after some of the purchases under LvG and Moyes, the LAST thing we need is more squad players.