My argument is if it was easy to score in La Liga then way aren't other players getting 30+ goals in the league every season? In fact its only Messi and Ronaldo who have scored 30+ goals in the league since a certain Diego Forlán for Atlético in 08-09. That was six seasons ago. You have to go back to 96-97 to find another player who registered 30+ goals in the league (Ronaldo for Barcelona if you were wondering). The fact remains and the evidence is there that you have to be a fairly good player to post 30 or more league goals.
Messi and Ronaldo are the best certainly in the last 7-8 years and their records are insane. They are scoring for fun in the champions league too, which is supposed to be the best competition in the world.
Let's have a look at other players. Sergio Aguero? He was a pretty decent striker at Atlético, signed as a teenager for a what was a massive €23 million at the time. He spent five seasons with Atlético his best season in 2010-11 (in terms of goals) he got 20. He left for Manchester City that summer and in his first season in the Premier league he got 23. This season with three games left he could beat that record as he currently has 22 for the league season.
Diego Costa had a phenomenal season in 2013-14 for Atlético, scoring 27. It was however his only season in which he post more than 10 goals in the Primera División. He's been injured on and off since the tail-end of last season but still managed 19 goals so far in his debut season for Chelsea in the Premier League playing significantly less minutes than last season.
Alexis Sánchez is one of the stars of the Premier League currently has 16 in his debut season with four games to play. He had his best ever La Liga scoring season last year and got 19, before that he the highest he scored was 11 in his debut season.
Staying with Arsenal, Santi Cazorla in his nine seasons in La Liga never got any higher than 9 goals. In his first Premier League season he got 12, he currently is on 7 goals with four games to play.
Fernando Torres the best he managed in Spain was the 20 he scored in 2003-04. He moved to Liverpool in 2007 and in his first season he got 24, injuries in the followed two seasons limited his tally to 14 and 18.
Oh but it's only players at the big clubs your looking at so far? Well Leicester in the relegation battle have Leonardo Ulloa who currently has 10 goals so far, he was with Almería in 2010-11 and got 7 goals.
Michu, remember him? He was Swansea' top scorer in 2012-13 with 18 goals. With Rayo the previous season, playing 200 more minutes he scored 15.
The other way, we have Gareth Bale. He carried Tottenham on his shoulders in the 2012-13 season scoring some absolute belters. He posted 21 that season. He moved to Real Madrid and playing for one of the best teams he got 15 goals. This season with three games left he has 13 goals, unlikely to beat the 21 he scored in his final Premier league season.
Luis Suárez almost fired Liverpool to a first ever Premier League title last season, he fired in 31 goals on the way (which remarkably wasn't his best goalscoring season, that was the 35 he got in 09-10 for Ajax). He missed the first two months of the current La Liga season and has 16 goals, which is still behind the 23 he got in 2012-13.
Other former La Liga players who have better scoring records in England are Rafael Van der Vaart, David Silva, Yaya Touré and Martin Petrov. They could be joined by Ander Herrera, Philipe Coutinho and Eduardo Vargas if those players score one more goal in the remaining three games this season.
I'll leave you with my favorite one. It involves Aston Villa signing Antonio Luna in 2013. In seven seasons Luna played in la Liga he scored 1 goal. It took him 85 minutes of his debut Premier League campaign to equal that tally, and he is a left back.
So for every Roberto Soldado you have a Sergio Aguero. For Arouna Koné you have Leonardo Ulloa and of course for Fábregas you can just Van Der Vaart or even Yaya Touré.
To summarize, no it's not easier to score in La Liga. If anything its easier to score in England.